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Astrophysical Solutions are Incompatible with the Solar Neutrino Data ; We consider the most general solar model, using the neutrino fluxes as free parameters constrained only by the solar luminosity, and show that the combined solar neutrino data exclude any astrophysical solution at 98 C.L. Our best fit to the 7Be and 8B fluxes is respectively 7 and 37pm4 of the standard solar model prediction, but only with a large chi2 5.6 for 1 d.f.. This best fit to the fluxes contradicts explicit nonstandard solar models, which generally reduce the 8B flux more than the 7Be. Those models are well parameterized by a single parameter, the central temperature. |
Model for a Light Z' Boson ; A model of a light Z' boson is constructed and phenomenological bounds are derived. This Z' boson arises from a very simple extension to the Standard Model, and it is constrained to be light because the vacuum expectation values which generate its mass also break the electroweak gauge group. It is difficult to detect experimentally because it couples exclusively or primarily depending on symmetry breaking details to second and third generation leptons. However, if the Z' boson is sufficiently light, then there exists the possibility of the twobody decay tau rightarrow mu Z' occuring. This will provide a striking signature to test the model. |
A Vectorlike Extension of the Standard Model ; A vectorlike extension of the standard model for heavier quarks and leptons with SU2times U1 gauge symmetry and only one Higgs doublet is examined. This scheme incorporates infinitely many fermions and avoids the appearance of a strongly interacting sector. The model is perturbatively well controllable, and constraints such as brightarrow sgamma and GIM suppression in general are naturally satisfied if the onset of heavier fermion mass scale is chosen at a few TeV. In this scheme, the physical Higgs particle generally mediates leptonic as well as quark flavorchanging processes at a rate below the present experimental limit. Vectorlike models, if suitably defined, provide a viable and interesting scheme for physics beyond 1 TeV. |
Deriving Nondecoupling Effects of Heavy Fields from the Path Integral a Heavy Higgs Field in an SU2 Gauge Theory ; We describe a method to remove nondecoupling heavy fields from a quantized field theory and to construct a lowenergy oneloop effective Lagrangian by integrating out the heavy degrees of freedom in the path integral. We apply this method to the Higgs boson in a spontaneously broken SU2 gauge theory gauged linear sigmamodel. In this context, the backgroundfield method is generalized to the nonlinear representation of the Higgs sector by applying a generalization of the Stueckelberg formalism. The background gaugeinvariant renormalization is discussed. At one loop the log MHterms of the heavyHiggs limit of this model coincide with the UVdivergent terms of the corresponding gauged nonlinear sigmamodel, but vertex functions differ in addition by finite constant terms in both models. These terms are also derived by our method. Diagrammatic calculations of some vertex functions are presented as consistency check. |
Axino Mass in Supergravity Models ; We analyze the mass of the axino, the fermionic superpartner of the axion, in general supergravity models incorporating a PecceiQuinnsymmetry and determine the cosmological constraints on this mass. In particular, we derive a simple criterion to identify models with an LSPaxino which has a mass of Om322fPQOkeV and can serve as a candidate for warm dark matter. We point out that such models have very special properties and in addition, the small axino mass has to be protected against radiative corrections by demanding small couplings in the PecceiQuinnsector. Generically, we find an axino mass of order m32. Such masses are constrained by the requirement of an axino decay which occurs before the decoupling of the ordinary LSP. Especially, for a large PecceiQuinnscale fPQ1011 GeV this constraint might be difficult to fulfill. |
Modelindependent Representation of Electroweak Data ; General modelindependent expressions are developed for the polarized and unpolarized crosssections for eeto fbar f near the Z0 resonance. The expressions assume only the analyticity of Smatrix elements. Angular dependence is included by means of a partial wave expansion. The resulting simple forms are suitable for use in fitting data or in Monte Carlo event generators. A distinction is made between modelindependent and modeldependent QED corrections and a simple closed expression is given for the effect of initialfinal state bremsstrahlung and virtual QED corrections. |
Proton Stability and Small Neutrino Mass in String Inspired E6 Models ; We propose a new possibility to realize simultaneously the sufficient proton stability and the interesting structure of neutrino mass matrix in superstring inspired E6 models. In this model the leptons and Higgs fields are assigned to a fundamental representation bf 27 in the different way among generations. Two pairs of Higgs doublets naturally remain light from three generation ones by imposing certain discrete symmetries, although all extra color triplets become sufficiently heavy. Under these symmetries suitable muterms to bring appropriate vacuum expectation values are prepared and the dangerous FCNC is avoidable. Some related phenomena to this model, especially, the structure of neutrino mass matrix are also discussed. |
Nonequilibrium dynamics preheating in the SU2 Higgs model ; The term preheating' has been introduced recently to denote the process in which energy is transferred from a classical inflaton field into fluctuating field particle degrees of freedom without generating yet a real thermal ensemble. The models considered up to now include, besides the inflaton field, scalar or fermionic fluctuations. On the other hand the typical ingredient of an inflationary scenario is a nonabelian spontaneously broken gauge theory. So the formalism should also be developed to include gauge field fluctuations excited by the inflaton or Higgs field. We have chosen here, as the simplest nonabelian example, the SU2 Higgs model. We consider the model at temperature zero. From the technical point of view we generalize an analytical and numerical renormalized formalism developed by us recently to coupled channnel systems. We use the 't HooftFeynman gauge and dimensional regularization. We present some numerical results but reserve a more exhaustive discussion of solutions within the paramter space of two couplings and the initial value of the Higgs field to a future publication. |
FineTuning Problem in a LeftRight Symmetric Model and Sogami's Generalized Covariant Derivative Method ; We study Sogami's generalized covariant derivative method for a SU2L times SU2R times U1BL times SU3c model that contains bidoublet and triplet Higgs bosons. In particular, a detailed study is made on the minimization conditions of the Higgs potential. It is known that a minimization condition and certain phenomenology for a extra gauge boson mass derive a restriction on potential parameters, which requires finetuning. We show that the restriction can be reduced to a condition of Yukawa coupling constants giving a heavy mass of the righthanded tau neutrino in our model. We also discuss the consistency among parameter restrictions of our model by taking phenomenology of the Higgs boson masses into account. |
On the Phase Diagram of QCD ; We analyze the phase diagram of QCD with two massless quark flavors in the space of temperature, T, and chemical potential of the baryon charge, mu, using available experimental knowledge of QCD, insights gained from various models, as well as general and model independent arguments including continuity, universality, and thermodynamic relations. A random matrix model is used to describe the chiral symmetry restoration phase transition at finite T and mu. In agreement with general arguments, this model predicts a tricritical point in the T mu plane. Certain critical properties at such a point are universal and can be relevant to heavy ion collision experiments. |
Models of Supersymmetric U2times U1 Flavor Symmetry ; We use a U2times U1 horizontal symmetry in order to construct supersymmetric models where the flavor structure of both quarks and leptons is induced naturally. The supersymmetric flavor changing neutral currents problem is solved by the degeneracy between sfermions induced by the U2 symmetry. The additional U1 enables the generation of mass ratios that cannot be generated by U2 alone. The resulting phenomenology differs from that of models with either abelian or U2times GUT symmetries. Our models give rise to interesting neutrino spectra, which can incorporate the SuperKamiokande results regarding atmospheric neutrinos. |
Radiative corrections to e e to H H THDM versus MSSM ; One loop radiative corrections to eeto H H are considered at future linear collider energies, in the general type II Two Higgs Doublet Model THDM and in the Minimal Supersymmetric Standard Modellike MSSM Higgs sector. To make the comparison between THDM and MSSM tractable, we have introduced a quasiSUSY parameterization which preserves all the treelevel Higgs masssumrules of the MSSM, and involves just 3 free parameters in the Higgs sector instead of 7 in the general THDM and comprises the MSSM as a particular case. The modelindependent soft photon contribution is isolated and shown to be substantial. Important effects come also from the contribution of the model dependent h0 H H and H0 H H vertices to the final state. In the MSSM, the contribution of the Higgs sector is moderate a few percent while in the THDM and both for small and large tan beta important effects sim 30 can be found. |
Top Quark Seesaw Theory of Electroweak Symmetry Breaking ; We study electroweak symmetry breaking involving the seesaw mechanism of quark condensation. These models produce a composite Higgs boson involving the lefthanded top quark, yet the top mass arises naturally at the observed scale. We describe a schematic model which illustrates the general dynamical ideas. We also consider a generic lowenergy effective theory which includes several composite scalars, and we use the effective potential formalism to compute their spectrum. We develop a more detailed model in which certain features of the schematic model are replaced by additional dynamics. |
Flat directions, String Compactification and 3 Generation Models ; We show how identification of absolutely flat directions allows the construction of a new class of compactified string theories with reduced gauge symmetry that may or may not be continuously connected to the original theory. We use this technique to construct a class of 3 generation models with just the Standard Model gauge group after compactification. We discuss the lowenergy symmetries necessary for a phenomenologically viable lowenergy model and construct an example in which these symmetries are identified with string symmetries which remain unbroken down to the supersymmetry breaking scale. Remarkably the same symmetry responsible for stabilising the nucleon is also responsible for ensuring one and only one pair of Higgs doublets is kept light. We show how the string symmetries also lead to textures in the quark and lepton mass matrices which can explain the hierarchy of fermion masses and mixing angles. |
Phase Effect of A General TwoHiggsDoublet Model in bto s ; In a general twoHiggsdoublet model 2HDM, without the it ad hoc discrete symmetries to prevent treelevel flavorchangingneutral currents, an extra phase angle in the chargedHiggsfermion coupling is allowed. We show that the chargedHiggs amplitude interferes destructively or constructively with the standard model amplitude depending crucially on this phase angle. The popular model I and II are special cases of our analysis. As a result of this phase angle the severe constraint on the chargedHiggs boson mass imposed by the inclusive rate of bto sgamma from CLEO can be relaxed. We also examine the effects of this phase angle on the neutron electric dipole moment. Furthermore, we also discuss other constraints on the chargedHiggsfermion couplings coming from measurements of B0barB0 mixing, rho0, and Rb. |
Triple and Quartic Interactions of Higgs Bosons in the General TwoHiggsDoublet Model ; In the case of minimal supersymmetric extension of the Standard Model MSSM, when the pseudoscalar Higgs boson mass is less than the supersymmetry energy scale, the effective theory at the electroweak scale is a twoHiggsdoublet model. We diagonalize the mass matrix of the general twoHiggsdoublet model, expressing Higgs boson selfcouplings in terms of two mixing angles and four Higgs boson masses, and derive in a compact form the complete set of Feynman rules, including quartic couplings in the Higgs sector, for the case of CPviolating potential. Some processes of double and triple Higgs boson production at a highenergy linear collider are calculated in the case of mixing angles and scalar boson masses satisfying the MSSM constraints. |
Flatons and PecceiQuinn Symmetry ; We study in detail a supersymmetric PecceiQuinn model, which has a DFSZ and a KSVZ version. The fields breaking the PecceiQuinn PQ symmetry correspond to flat directions flaton fields and have unsuppressed couplings when PQ symmetry is unbroken. The models have interesting particle physics phenomenology. The PQ scale is naturally generated through radiative corrections; also, in the DFSZ case the mu problem can be solved and neutrino masses can be generated. Cosmologically they lead to a short period of thermal inflation making the axion an excellent dark matter candidate if one of the flaton fields has a positive effective masssquared at early times but with too low a density in the opposite case. A highly relativistic population of axions is produced by flaton decay during the subsequent reheating, whose density is constrained by nucleosynthesis. We evaluate all of the relevant reaction rates and evaluate the nucleosynthesis constraint. We find that the KSVZ model is practically ruled out, while the DFSZ model has a sizable allowed region of parameter space. |
Composite photon and Wpm, Z0 vector bosons from a topcondensation model at fixed v 247 GeV ; Starting from the historical Fermi fourfermion lowenergy effective electroweak interactions Lagrangian for the third generation of quarks, augmented by an NJL type interaction responsible for dynamical symmetry breaking and heavy quark mass generation, and fixing the scalar Higgs field v.e.v. at v 247 GeV, we show that 1 heavy quark bound states Qbar Q with quantum numbers of the Wpm bosons exist for arbitrarily weak positive vector coupling GF, so long as the quark mass is sufficiently large; 2 a massive composite neutral vector boson Z0 appears; 3 a massless composite parityconserving neutral vector boson gamma appears, the composite HiggsKibble ghosts decouple from the quarks and other particles, the longitudinal components of the vector boson propagators vanish, as GF to GFexpt 1sqrt2 v2, which also implies that the cutoff Lambda to infty. Thus, the Fermi interaction model is equivalent to a locally gauge invariant theory but with definite values of coupling constants and masses. The model discussed here was chosen for illustrative purposes and is not equivalent to the Standard Model. |
A Real CKM Matrix and Physics Beyond the Standard Model ; We study the possible existence of a real CabibboKobayashiMaskawa CKM matrix, with CP violation originating from physics beyond the standard model SM. We show that present experimental data allow for a real CKM matrix provided that new physics also contributes to Delta mBd by at least 20 of the SM contribution for rho 0, besides generating CP violation in the kaon sector. The naturalness of a real CKM matrix is studied within the framework of general multiHiggsdoublet models with spontaneous CP violation. As an example, we discuss a specific twoHiggsdoublet model and its implications for CP asymmetries in nonleptonic neutral Bmeson decays. |
F0barF0 Mixing and CP Violation in the General Two Higgs Doublet Model ; A phenomenological analysis of the general two Higgs doublet model is presented. Possible constraints of the Yukawa couplings are obtained from the K0barK0, B0barB0 and D0barD0 mixings. A much larger D0barD0 mixing than the standard model prediction is possible. It is shown that the emerging of various new sources of CP violation in the model could strongly affect the determination of the unitarity triangle. It can be helpful to look for a signal of new physics by comparing the extracted angle beta from two different ways, such as from the process Bto Jpsi KS and from fitting the quantities Vub, Delta mB and epsilon. |
Radiatively Generated Neutrino Masses in SU3L x U1N Gauge Models ; In SU3L x U1N gauge models for electroweak interactions, we discuss how to implement a radiative mechanism of generating Majorana neutrino masses by considering the property that the Higgs scalar, which has a coupling to a charged lepton ellneutrino nu pair, is naturally included. The mechanism is shown to work in models with a heavy charged lepton, omega, in a lepton triplet nu, ell, omega and with a heavy neutral lepton, N, in nu, ell, N. A minimal model with ell and ellc in nu, ell, ellc together with a sextet Higgs scalar suffers from a finetuning problem to suppress treelevel neutrino masses. |
Naturalness and Supersymmetry ; Supersymmetry solves the gauge hierarchy problem of the Standard Model if the masses of supersymmetric partners of the SM particles are close to the weak scale. In this thesis, we argue that the supersymmetric Standard Model, while avoiding the fine tuning in electroweak symmetry breaking, requires unnaturalnessfine tuning in some other sector of the theory. For example, Baryon and Lepton number violating operators are allowed which lead to proton decay and flavor changing neutral currents. We study some of the constraints from the latter in this thesis. We have to impose an Rparity for the theory to be both natural and viable. In the absence of flavor symmetries, the supersymmetry breaking masses for the squarks and sleptons lead to too large flavor changing neutral currents. We show that two of the solutions to this problem, gauge mediation of supersymmetry breaking and making the scalars of the first two generations heavier than a few TeV, reintroduce fine tuning in electroweak symmetry breaking. We also construct a model of low energy gauge mediation with a nonminimal messenger sector which improves the fine tuning and also generates required Higgs mass terms. We show that this model can be derived from a Grand Unified Theory despite the nonminimal spectrum. |
On the Structure Functions of Mesons and Baryons in a Chiral Quark Model ; This research summarizes work done by myself Nucl.Phys.bf A641 1998461, or in collaboration with R. M. Davidson Phys.Lett.bf B3481995163 and H. Weigel and L. Gamberg Nucl.Phys.bf B5601999xx. I will discuss several topics related with the computation of structure functions in the quark model in general and its perturbative evolution. In particular, I address this topic in the NambuJonaLasinio model of hadrons, where the nucleon is constructed as a soliton. I show that the handling of the regularization procedure is crucial in order to obtain exact scaling in the Bjorken limit and fulfillment of sum rules. I also include some problems concerning the general validity of quark model calculations. |
Radiative corrections to pair production of charged Higgs bosons at TESLA ; Charged Higgs particles are a common feature of many extensions of the Standard Model. While its existence with masses up to the TeV scale can be probed at the Tevatron Run II and LHC hadron colliders, a precise determination of its properties would have to wait for a high energy ee linear collider. We have computed the complete oneloop electroweak corrections to the crosssection for charged Higgs bosons pair production in ee collisions, in the framework of general Two Higgs Doublet Models, as well as the Minimal Supersymmetric Standard Model. A study is presented for typical values of the model parameters, showing the general behaviour of the corrections. |
Bulk Fields and Supersymmetry in a Slice of AdS ; Fivedimensional models where the bulk is a slice of AdS have the virtue of solving the hierarchy problem. The electroweak scale is generated by a warp'' factor of the induced metric on the brane where the standard model fields live. However, it is not necessary to confine the standard model fields on the brane and we analyze the possibility of having the fields actually living in the slice of AdS. Specifically, we study the behaviour of fermions, gauge bosons and scalars in this geometry and their implications on electroweak physics. These scenarios can provide an explanation of the fermion mass hierarchy by warp factors. We also consider the case of supersymmetry in the bulk, and analyze the conditions on the mass spectrum. Finally, a model is proposed where the warp factor generates a small TeV supersymmetrybreaking scale, with the gauge interactions mediating the breaking to the scalar sector. |
Bounds for Lepton Flavor Violation and the Pseudoscalar Higgs in the General Two Higgs Doublet Model using g2 muon factor ; Current experimental data from the g2 muon factor, seems to show the necessity of physics beyond the Standard Model SM, since the difference between SM and experimental predictions is 2.6sigma . In the framework of the General Two Higgs Doublet Model 2HDM, we calculate the muon anomalous magnetic moment to get lower and upper bounds for the Flavour Changing FC Yukawa couplings in the leptonic sector. We also obtain lower bounds for the mass of the pseudoscalar Higgs mA0 as a function of the parameters of the model. |
etap K puzzle of B meson decays and new physics effects in the general twoHiggsdoublet model ; we calculate the new physics contributions to seven measured decays B to pi pi, K pi and K etap in the general twoHiggsdoublet model Model III. Within the considered parameter space, we find that a the CLEOBaBar measurement of Bto pi pi decay prefers a small F0Bpi0 F0Bpi00.25 pm 0.03; b the new physics enhancements to the penguindominated B to Kpi and Bto K etap decays are significant in size, sim 4070 w.r.t the standard model predictions; and c the new physics enhancements can boost the branching ratios cal BB to K etap and cal BB to K0 etap to be consistent with the data within one standard deviation, and hence lead to a simple and plausible new physics interpretation for the etap K puzzle. |
How Can a Heavy Higgs Boson be Consistent with the Precision Electroweak Measurements ; The fit of precision electroweak data to the Minimal Standard Model currently gives an upper limit on the Higgs boson mass of 170 GeV at 95 confidence. Nevertheless, it is often said that the Higgs boson could be much heavier in more general models. In this paper, we critically review models that have been proposed in the literature that allow a heavy Higgs boson consistent with the precision electroweak constraints. All have unusual features, and all can be distinguished from the Minimal Standard Model either by improved precision measurements or by other signatures accessible to nextgeneration colliders. |
New physics effects to the lepton polarizations in the B K l l decay ; Using the general, model independent form of the effective Hamiltonian, the general expressions of the longitudinal, normal and transversal polarization asymmetries for l and l and combinations of them for the exclusive B K l l decay are found. The sensitivity of lepton polarizations and their combinations on new Wilson coefficients are studied. It is found that there exist regions of Wilson coefficients for which the branching ratio coincides with the Standard Model result while the lepton polarizations differ substantially from the standard model prediction. Hence, studying lepton polarization in these regions of new Wilson coefficients can serve as a promising tool for establishing new physics beyond the Standard Model. |
Large Extra Dimensions from a Small Extra Dimension ; Models with extra dimensions have changed our understanding of the hierarchy problem. In general, these models explain the weakness of gravity by diluting gravity in a large bulk volume, or by localizing the graviton away from the standard model. In this paper, we show that the warped geometries necessary for the latter scenario can naturally induce the large volumes necessary for the former. We present a model in which a large volume is stabilized without supersymmetry. We comment on the phenomenology of this scenario and generalizations to additional dimensions. |
B Xs l l in the vectorlike quark model ; We extend the standard model by adding an extra generation of isosinglet up and downtype quark pair which engage in weak interactions only via mixing with the three ordinary quark families. It is shown that the generalized 4times 4 quark mixing matrix, which is necessarily nonunitary, leads to nonvanishing flavor changing neutral currents. We then proceed to investigate various distributions and total branching ratio of the inclusive B Xs l l l e,mu rare B decays in the context of this model. It is shown that the shapes of the differential branching ratio and forwardbackward asymmetry distribution are very sensitive to the value of the model parameters which are constrained by the experimental upper bound on BRB Xs mu mu. We also indicate that, for certain values of the dileptonic invariant mass, CP asymmetries up to 10 can be obtained. |
The exclusive Bto ell ell and Bto ell ell decays in the general two Higgs doublet model ; We study the differential branching ratio, branching ratio and the forwardbackward asymmetry for the exclusive B to pi ell ell and B to rho ell ell decays in the general two Higgs doublet model including the neutral Higgs boson effects. We analyze the dependencies of these quantities on the neutral Higgs boson contributions and the other model parameters. We observe that two Higgs doublet model with the neutral Higgs boson exchanges gives quite sizable contributions to these observables for both channels we consider. Since the neutral Higgs boson exchanges are the only source of the forwardbackward asymmetry for B to pi tau tau decay, which is at the order of magnitude 110, measurement of this observable is promising to determine the neutral Higgs boson effects. |
Charged particle fluctuations and microscopic models of nuclear collisions ; We study the eventbyevent fluctuations of the charged particles and compare the results of different MonteCarlo Generators MCG VNIb, HIJING, HIJINGBbar B and RQMD. We find that the Dmeasure can be used to distinguish between the different gluon populations that are present in the MCG models. On the other hand, the value of the Dmeasure shows high sensitivity to the rescattering effects in VNIb model, but lower sensitivity to the rescattering effects in RQMD model. We also find that the Dmeasures from AA are consistent with the Dmeasures from pp for all generators except VNIb. Therefore, any deviation among the values of Dmeasure for different impact parameters and between pp and AA collisions may indicate that either the rescattering effects play a key role in the interactions or there is new physics in AA collisions. |
A minimal three generation seesaw scenario for LSND ; We show that in the minimal three generation seesaw models for neutrinos, the presence of leptonic LeLmuLtautimes S2 symmetry leads to one of the right handed neutrinos remaining massless. This state can then be identified with the sterile neutrino required for a simultaneous understanding of solar, atmospheric and LSND observations. We present a gauge model where the presence of higher dimensional operators originating from Planck scale physics lead to a realistic 22 mixed scenario that fits all oscillation data. The model predicts a range for the mixing angle Ue3 and an effective mass for neutrinos emitted in tritium decay, which can be used to test this model. |
B to , K , K etap decays and new physics effects in the general twoHiggsdoublet model an update ; In this paper, we reexamine the new physics contributions to seven well measured B to PP decays in the standard model SM and the general twoHiggsdoublet model model III and compare the theoretical predictions with the new data. Within the considered parameter space we found that a the measurements of the branching ratios for Bto pi pi, K pi and K0 pi lead to a strong constraint on the form factor F0Bpi0 F0Bpi00.24 pm 0.03; b the new physics enhancements to the penguindominated B to K pi and K etap decays are significant in size, sim 4065 w.r.t the SM predictions, and play an important role in restoring the consistency between the data and the theory. |
Large Scale Structure from the Higgs fields of the Supersymmetric Standard Model ; We propose an alternative implementation of the curvaton mechanism for generating the curvature perturbations which does not rely on a late decaying scalar decoupled from inflation dynamics. In our mechanism the supersymmetric Higgs scalars are coupled to the inflaton in a hybrid inflation model, and this allows the conversion of the isocurvature perturbations of the Higgs fields to the observed curvature perturbations responsible for large scale structure to take place during reheating. We discuss an explicit model which realises this mechanism in which the mu term in the Higgs superpotential is generated after inflation by the vacuum expectation value of a singlet field. The main prediction of the model is that the spectral index should deviate significantly from unity, n1sim 0.1. We also expect relic isocurvature perturbations in neutralinos and baryons, but no significant departures from gaussianity and no observable effects of gravity waves in the CMB spectrum. |
Are supersymmetric models with large tanbeta natural ; We point out that, contrary to general belief, generic supersymmetric models are not technically unnatural in the limit of very large values of the parameter tanbeta when radiative corrections are properly included. Rather, an upper limit on tanbeta only arises from the requirement that Yukawa couplings remain perturbative up to some high scale. We quantify the relation between this scale and the maximum value of tanbeta. Whereas tanbeta is limited to lie below 5070 in the mSUGRA model, models with a much lower scale of new physics beyond supersymmetry may have tanbeta 150200. |
Twoloop Neutrino Mass Generation and its Experimental Consequences ; If neutrino masses have a radiative origin, their smallness can be naturally understood even when lepton number violation occurs near the weak scale. We analyze a specific model of this type wherein the neutrino masses arise as twoloop radiative corrections. We show that the model admits the near bimaximal mixing pattern suggested by the current neutrino oscillation data. Unlike the conventional seesaw models, these twoloop models can be directly tested in lepton flavor violating decays tau 3 mu and mu e gamma as well as at colliders by the direct observation of charged scalars needed for the mass generation. It is shown that consistency with the neutrino oscillation data requires that the leptonic rare decays should be within reach of forthcoming experiments and that the charged scalars are likely to be within reach of the LHC. |
Escape from washing out of baryon number in a twozerotexture general Zee model compatible with the large mixing angle MSW solution ; We propose a twozerotexture general Zee model, compatible with the large mixing angle MikheyevSmirnovWolfenstein solution. The washing out of the baryon number does not occur in this model for an adequate parameter range. We check the consistency of a model with the constraints coming from flavor changing neutral current processes, the recent cosmic microwave background observation, and the Zburst scenario. |
Upper bounds on the mass of the lightest neutralino ; We derive the general upper bounds on the mass of the lightest neutralino, as a function of the gluino mass, in different supersymmetry breaking models with minimal particle content and the standard model gauge group. This includes models with gravity mediated supersymmetry breaking SUGRA, as well as models with anomaly mediated supersymmetry breaking AMSB. We include the nexttoleading order corrections in our evaluation of these bounds. We then expand the mass matrix in powers of MZmu, and find the upper bound on the mass of the lightest neutralino from this expansion. By scanning over all of the parameter space, we find that the bound we have obtained can be saturated. We compare the general upper bound on the lightest neutralino mass to the upper bound that is obtained when the radiative electroweak symmetry breaking scenario is assumed. |
Supersymmetry Breaking in Warped Geometry ; We examine the soft supersymmetry breaking parameters in supersymmetric theories on a slice of AdS5 which generate the hierarchical Yukawa couplings by dynamically localizing the bulk matter fields in extra dimension. Such models can be regarded as the AdS dual of the recently studied 4dimensional models which contain a supersymmetric CFT to generate the hierarchical Yukawa couplings. In such models, if supersymmetry breaking is mediated by the bulk radion superfield andor some brane chiral superfields, potentially dangerous flavorviolating soft parameters can be naturally suppressed, thereby avoiding the SUSY flavor problem. We present some models of radiondominated supersymmetry breaking which yield a highly predictive form of soft parameters in this framework. |
Varying alpha, thresholds and extra dimensions ; We consider variations of coupling strengths and mass ratios in and beyond the Standard Model, in the light of various mechanisms of mass generation. In fourdimensional unified models, heavy quark and superparticle thresholds and the electron mass can completely alter the testable relation between Delta ln alpha and Delta ln mu, where mu equiv mpme. In extradimensional models where a compactification scale below the fundamental scale is varying, definite predictions may result even without unification; we examine some models with ScherkSchwarz supersymmetrybreaking. |
Probing the charged Higgs quantum numbers through the decay H W h0 ; The vertex Halpha Wh0beta, involving the gauge boson W and the charged Halpha and neutral Higgs bosons h0beta, arises within the context of many extensions of the SM, and it can be used to probe the quantum numbers of the Higgs multiplet. After presenting a general discusion for the expected form of this vertex with arbitrary Higgs representations, we discuss its strength for several specific models, which include i the TwoHiggs Doublet Model THDM, both the generic and the SUSY case, and ii models with additional Higgs triplets, including both SUSY and nonSUSY cases. We find that in these models, there are regions of parameters where the decay Halpha W h0beta, is kinematically allowed, and reaches Branching Ratios BR that may be detectable, thus allowing to test the properties of the Higgs sector. |
Generalized sum rules of the nucleon in the CQM ; The sum rules serve a powerful tool to study the nucleon structure by providing a bridge between the statical properties of the nucleon such as electrical charge, and magnetic moment and the dynamical properties e.g. the transition amplitudes to excited states in a wide range of energy and momentum transfer Q2. We study the generalized sum rules of the nucleon in the framework of the constituent quark model. We use two different CQM, the one with the hypercentral potential citehccqm1, citehccqm2, citehccqm3, and with the harmonic oscillator potential citeKI, both with only few parameters fixed to the baryonic spectrum. We confront our results to the model independent sum rules and to the predictions of the phenomenological MAID citeMAID model and find that in all the cases considered, in the intermediate Q2 range 0.21.5 GeV2, both CQM models provide a good description of the sum rules on the neutron. |
Realistic Neutrino Masses from Multibrane Extensions of the RandallSundrum Model ; Scenarios based on the existence of large or warped RandallSundrum model extra dimensions have been proposed for addressing the long standing puzzle of gauge hierarchy problem. Within the contexts of both those scenarios, a novel and original type of mechanism generating small Dirac neutrino masses, which relies on the presence of additional righthanded neutrinos that propagate in the bulk, has arisen. The main objective of the present study is to determine whether this geometrical mechanism can produce reasonable neutrino masses also in the interesting multibrane extensions of the RandallSundrum model. We demonstrate that, in some multibrane extensions, neutrino masses in agreement with all relevant experimental bounds can indeed be generated but at the price of a constraint stronger than the existing ones on the bulk geometry, and that the other multibrane models even conflict with those experimental bounds. |
Rsymmetries from higher dimensions ; The supersymmetric extensions of the Standard Model can tolerate quite a large hierarchy between various supersymmetry breaking terms, a good example being the models of split supersymmetry. However, theoretical models generating such a stable hierarchy are not so easy to construct. An interesting idea consists in coupling the brane localized gauge sector to extended supergravities in the bulk of extra dimensions, and using different sources of supersymmetry breaking in the bulk and on the brane. This in principle allows one to separate the magnitude of the gravitino mass from the supersymmetry breaking masses of gaugini and of charged matter. In this paper we present a detailed analysis of a simple field theoretical model where such an idea is realized. Departure from this symmetric set of boundary conditions breaks Rsymmetry, and gaugino masses are generated at oneloop order, however the magnitude of the resulting soft gaugino masses is proportional to the Rsymmetry breaking Majoranatype gravitino mass which is continously deformable to zero. |
Precise Calculation of the Relic Density of KaluzaKlein Dark Matter in Universal Extra Dimensions ; We revisit the calculation of the relic density of the lightest KaluzaKlein particle LKP in the model of Universal Extra Dimensions. The KaluzaKlein KK particle spectrum at level one is rather degenerate, and various coannihilation processes may be relevant. We extend the calculation of hepph0206071 to include coannihilation processes with all level one KK particles. In our computation we consider a most general KK particle spectrum, without any simplifying assumptions. In particular, we do not assume a completely degenerate KK spectrum and instead retain the dependence on each individual KK mass. As an application of our results, we calculate the KaluzaKlein relic density in the Minimal UED model, turning on coannihilations with all level one KK particles. We then go beyond the minimal model and discuss the size of the coannihilation effects separately for each class of level 1 KK particles. Our results provide the basis for consistent relic density computations in arbitrarily general models with Universal Extra Dimenions. |
The flavor of productgroup GUTs ; The doublettriplet splitting problem can be simply solved in productgroup GUT models, using a global symmetry that distinguishes the doublets from the triplets. Apart from giving the required mass hierarchy, this triplet symmetry'' can also forbid some of the triplet couplings to matter. We point out that, since this symmetry is typically generationdependent, it gives rise to nontrivial flavor structure. Furthermore, because flavor symmetries cannot be exact, the tripletmatter couplings are not forbidden then but only suppressed. We construct models in which the triplet symmetry gives acceptable proton decay rate and fermion masses. In some of the models, the prediction mb mtau is retained, while the similar relation for the first generation is corrected. Finally, all this can be accomplished with triplets somewhat below the GUT scale, supplying the right correction for the standard model gauge couplings to unify precisely. |
Neutrino Mass Through Concomitant Breakdown of the U1 Chiral and Scale Symmetries ; The possibility of generating neutrino mass through seesaw mechanism involving U1 chiral PecceiQuinn and scale symmetries breakdown is discussed. We consider a generic scale invariant model which has three Majorana fermions and a complex scalar singlet, which might be the one responsible for an invisible axion, and we perform a summation of all leading logarithmic radiative corrections to the tree level potential. The effective potential so obtained is stable and drives the scalar field to a nonzero vacuum expectation value according to the ColemanWeinberg mechanism. As a result, righthanded neutrinos gain mass at the PecceiQuinn scale which is suggestive for explaining very light active neutrinos. We illustrate the whole idea with the addition of the Standard Model, and also a SU3LotimesU1X model in which the subgroup SU2LotimesU1Y is constrained to be broken as an effect of the effective potential. This last model presents electric charge quantization as well. |
The discrete flavor symmetry D5 ; We consider the standard model SM extended by the flavor symmetry D5 and search for a minimal model leading to viable phenomenology. We find that it contains four Higgs fields apart from the three generations of fermions whose left and lefthanded conjugate parts do not transform in the same way under D5. We provide two numerical fits for the case of Dirac and Majorana neutrinos to show the viability of our low energy model. The fits can accommodate all data with the neutrinos being normally ordered. For Majorana neutrinos two of the righthanded neutrinos are degenerate. Concerning the Higgs sector we find that all potentials constructed with three SMlike Higgs doublets transforming as 12 under D5 have a further unwanted global U1 symmetry. Therefore we consider the case of four Higgs fields forming two D5 doublets and show that this potential leads to viable solutions in general, however it does not allow spontaneous CPviolation SCPV for an arbitrary vacuum expectation value VEV configuration. Finally, we discuss extensions of our model to grand unified theories GUTs as well as embeddings of D5 into the continuous flavor symmetries SO3f and SU3f. |
Dynamically Generated Open and Hidden Charm Meson Systems ; We will study open and hidden charm scalar meson resonances within two different models. The first one is a direct application of a chiral Lagrangian already used to study flavor symmetry breaking in Skyrme models. In another approach to the problem a SU4 symmetric Lagrangian is built and the symmetry is broken down to SU3 by identifying currents where heavy mesons are exchanged and suppressing those. Unitarization in couple channels leads to dynamical generation of resonances in both models, in particular a new hidden charm resonance with mass 3.7 GeV is predicted. The small differences between these models and with previous works will be discussed. |
ModelIndependent Description and Large Hadron Collider Implications of Suppressed TwoPhoton Decay of a Light Higgs Boson ; For a Standard Model Higgs boson with mass between 115 GeV and 150 GeV, the twophoton decay mode is important for discovery at the Large Hadron Collider LHC. We describe the interactions of a light Higgs boson in a more modelindependent fashion, and consider the parameter space where there is no twophoton decay mode. We argue from generalities that analysis of the tbar t h discovery mode outside its normally thought of range of applicability is especially needed under these circumstances. We demonstrate the general conclusion with a specific example of parameters of a type I twoHiggs doublet theory, motivated by ideas in strongly coupled model building. We then specify a complete set of branching fractions and discuss the implications for the LHC. |
Generalized Kontsevich Model Versus Toda Hierarchy and Discrete Matrix Models ; We represent the partition function of the Generalized Kontsevich Model GKM in the form of a Toda lattice taufunction and discuss various implications of nonvanishing negative and zerotime variables the appear to modify the original GKM action by negativepower and logarithmic contributions respectively. It is shown that so deformed taufunction satisfies the same string equation as the original one. In the case of quadratic potential GKM turns out to describe it forced Toda chain hierarchy and, thus, corresponds to a it discrete matrix model, with the role of the matrix size played by the zerotime at integer positive points. This relation allows one to discuss the doublescaling continuum limit entirely in terms of GKM, i.e. essentially in terms of it finitefold integrals. |
On RSOS models associated to Lie algebras and RCFT ; RSOS models based on the Lie algebras Bm, Cm and Dm are derived from the braiding of conformal field theory. This gives the first systematic derivation of these models earlier described by Jimbo et al. The general two field Boltzmann weights associated to any RCFT are described, giving in particular the off critical thermalized Boltzmann weights. Crossing properties are discussed and are shown to agree with the general theory which connects these with toroidal modular transformations. The soliton systems based on these lattice models are described and are conjectured based on the mass formulae and the spins of the integrals of motions to describe perturbations of the RCFT Gktimes G1over Gk1, where G is the corresponding Lie algebra. |
Integrable structures in matrix models and physics of 2dgravity ; A review of the appearence of integrable structures in the matrix model description of 2dgravity is presented. Most of ideas are demonstrated at the technically simple but ideologically important examples. Matrix models are considered as a sort of effective description of continuum 2d field theory formulation. The main physical role in such description is played by the VirasoroW constraints which can be interpreted as a certain unitarity or factorization constraints. Bith discrete and continuum Generalized Kontsevich models are formulated as the solutions to those discrete continuous VirasoroW constraints. Their integrability properties are proven using mostly the determinant technique highly related to the representation in terms of free fields. The paper also contains some new observations connected to formulation of more general than GKM solutions and deeper understanding of their relation to 2d gravity. |
On SWminimal models and N1 supersymmetric Quantum Todafield theories ; We construct free field representations of the SWalgebras SW32,2 and SW32,32,2 by using the corresponding TodaFieldTheories. In constructing the series of minimal models using covariant vertex operators, we find a necessary restriction on the Cartan matrix of the SuperLieAlgebra, also for the general case. Within this framework, this restriction claims that there be a minimum of one nonvanishing element on the diagonal of the Cartan matrix, which is without parallel in bosonic conformal field theory. As a consequence only two series of SSLA's yield minimal models, namely Osp2n2n1 and Osp2n2n1. Subsequently some general aspects of degenerate representations of SWalgebras, notably the fusion rules, are investigated. As an application we discuss minimal models of SW32,2, which were constructed with independent methods, in this framework. Covariant formulation is used throughout this paper. |
Uq osp2,2 Lattice Models ; In this paper I construct lattice models with an underlying Uq osp2,2 superalgebra symmetry. I find new solutions to the graded YangBaxter equation. These it trigonometric Rmatrices depend on it three continuous parameters, the spectral parameter, the deformation parameter q and the U1 parameter, b, of the superalgebra. It must be emphasized that the parameter q is generic and the parameter b does not correspond to the nilpotency' parameter of citegs. The rational limits are given; they also depend on the U1 parameter and this dependence cannot be rescaled away. I give the Bethe ansatz solution of the lattice models built from some of these Rmatrices, while for other matrices, due to the particular nature of the representation theory of osp2,2, I conjecture the result. The parameter b appears as a continuous generalized spin. Finally I briefly discuss the problem of finding the ground state of these models. |
Standard Model With Higgs As Gauge Field On Fourth Homotopy Group ; Based upon a first principle, the generalized gauge principle, we construct a general model with GLtimes G'R times Z2 gauge symmetry, where Z2pi4GL is the fourth homotopy group of the gauge group GL, by means of the noncommutative differential geometry and reformulate the WeinbergSalam model and the standard model with the Higgs field being a gauge field on the fourth homotopy group of their gauge groups. We show that in this approach not only the Higgs field is automatically introduced on the equal footing with ordinary YangMills gauge potentials and there are no extra constraints among the parameters at the tree level but also it most importantly is stable against quantum correlation. |
String Models for Locally Supersymmetric Grand Unification ; Phenomenologically viable string vacua may require incorporating KacMoody algebras at level geq 2. We exploit the free fermionic formulation to construct N0,2 worldsheet supersymmetric string models with specific phenomenological input N1 spacetime supersymmetry, three generations of chiral fermions in gauge groups SO10 or SU5, adjoint Higgses, and a single Yukawa coupling of a fundamental Higgs to the third generation. In this talk, we will show models of gauge group SO10 and of SU5 without any gauge singlet moduli, and show some novel features appearing in the connection of these two models. The accompanying, and rather nontrivial, discrete chiral subalgebras can determine hierarchies in the fermion mass matrix. Our approach to string phenomenology opens up the possibility of it concrete explorations of a wide range of proposals both for dynamical supersymmetry breaking and for the dynamics of the dilaton and other stringy moduli. Talk presented at DPF 94, Albuquerque, New Mexico |
The Topological GG WZW Model in the Generalized Momentum Representation ; We consider the topological gauged WZW model in the generalized momentum representation. The chiral field g is interpreted as a counterpart of the electric field E of conventional gauge theories. The gauge dependence of wave functionals Psig is governed by a new gauge cocycle phiGWZW. We evaluate this cocycle explicitly using the machinery of Poisson sigmamodels. In this approach the GWZW model is reformulated as a Schwarz type topological theory so that the action does not depend on the worldsheet metric. The equivalence of this new formulation to the original one is proved for genus one and conjectured for an arbitrary genus Riemann surface. As a byproduct we discover a new way to explain the appearance of Quantum Groups in the WZW model. |
Relativistic CalogeroSutherland Model Spin Generalization, Quantum Affine Symmetry and Dynamical Correlation Functions ; Spin generalization of the relativistic CalogeroSutherland model is constructed by using the affine Hecke algebra and shown to possess the quantum affine symmetry uqglt. The spinless model is exactly diagonalized by means of the Macdonald symmetric polynomials. The dynamical densitydensity correlation function as well as oneparticle Green function are evaluated exactly. We also investigate the finitesize scaling of the model and show that the lowenergy behavior is described by the C1 Gaussian theory. The results indicate that the excitations obey the fractional exclusion statistics and exhibit the TomonagaLuttinger liquid behavior as well. |
Yangian Symmetries in the SUN1 WZW Model and the CalogeroSutherland Model ; We study the SUN, level 1 WessZuminoWitten model, with affine primary fields as spinon fields of fundamental representation. By evaluating the action of the Yangian generators Q0a, Q1a and the Hamiltonian H2 on two spinon states we get a new connection between this conformal field theory and the CalogeroSutherland model with SUN spin. This connection clearly confirms the need for the W3 generator in H2 and an additional term in the Qa1. We also evaluate some energy spectra of H2, by acting it on multispinon states. |
Affine Toda Systems Coupled to Matter Fields ; We investigate higher grading integrable generalizations of the affine Toda systems. The extra fields, associated to non zero grade generators, obey field equations of the Dirac type and are regarded as matter fields. The models possess soliton configurations, which can be interpreted as particles of the theory, on the same footing as those associated to fundamental fields. A special subclass of these models is remarkable. They possess a U1 Noether current which, after a special gauge fixing of the conformal symmetry, is proportional to a topological current. This leads to the confinement of the matter field inside the solitons, which can be regarded as a one dimensional bag model for QCD. These models are also relevent to the study of electron selflocalization in quasionedimensional electronphonon systems. |
The Spectrum of Bogomol'nyi Solitons in Gauged Linear Sigma Models ; Gauged linear sigma models with Cmvalued scalar fields and gauge group U1d, d leq m, have soliton solutions of Bogomol'nyi type if a suitably chosen potential for the scalar fields is also included in the Lagrangian. Here such models are studied on 21dimensional Minkowski space. If the dynamics of the gauge fields is governed by a Maxwell term the appropriate potential is a sum of generalised Higgs potentials known as FayetIliopoulos Dterms. Many interesting topological solitons of Bogomol'nyi type arise in models of this kind, including various types of vortices e.g. NielsenOlesen, semilocal and superconducting vortices as well as, in certain limits, textures e.g. CPm1 textures and gauged CPm1 textures. This is explained and general results about the spectrum of topological defects both for broken and partially broken gauge symmetry are proven. When the dynamics of the gauge fields is governed by a ChernSimons term instead of a Maxwell term a different scalar potential is required for the theory to be of Bogomol'nyi type. The general form of that potential is given and a particular example is discussed. |
Dynamical Supersymmetry Breaking on Quantum Moduli Spaces ; Supersymmetry breaking by the quantum deformation of a classical moduli space is considered. A simple, nonchiral, renormalizable model is presented to illustrate this mechanism. The well known, chiral, SU3 times SU2 model and its generalizations are shown to break supersymmetry by this mechanism in the limit Lambda2 gg Lambda3. Other supersymmetry breaking models, with classical flat directions that are only lifted quantum mechanically, are presented. Finally, by integrating in vector matter, the strongly coupled region of chiral models with a dynamically generated superpotential is shown to be continuously connected to a weakly coupled description in terms of confined degrees of freedom, with supersymmetry broken at tree level. |
Algebraic Bethe ansatz for eight vertex model with general openboundary conditions ; By using the intertwiner and facevertex correpondence relation, we obtain the Bethe ansatz equation of eight vertex model with open boundary condtitions in the framework of algebraic Bethe ansatz method. The open boundary condition under consideration is the general solution of the reflection equation for eight vertex model with only one restriction on the free parameters of the right side reflecting boundary matrix. The reflecting boundary matrices used in this paper thus may have offdiagonal elements. Our construction can also be used for the Bethe ansatz of SOS model with reflection boundaries. |
Integrable Generalized Thirring Model ; We derive the conditions that the coupling constants of the Generalized Thirring Model have to satisfy in order for the model to admit an infinite number of commuting classical conserved quantities. Our treatment uses the bosonized version of the model, with periodic boundary conditions imposed on the space coordinate. Some explicit examples that satisfy these conditions are discussed. We show that, with a different set of boundary conditions, there exist additional conserved quantities, and we find the Poisson Bracket algebra satisfied by them. |
Sigmamodel for Generalized Composite pbranes ; A multidimensional gravitational model containing several dilatonic scalar fields and antisymmetric forms is considered. The manifold is chosen in the form M M0 x M1 x ... x Mn, where Mi are Einstein spaces i 0. The blockdiagonal metric is chosen and all fields and scale factors of the metric are functions on M0. For the forms composite electromagnetic pbrane ansatz is adopted. The model is reduced to gravitating selfinteracting sigmamodel with certain constraints. In pure electric and magnetic cases the number of these constraints is mm 12 where m is number of 1dimensional manifolds among Mi. In the electromagnetic case for dim M0 1, 3 additional m constraints appear. A family of MajumdarPapapetrou type solutions governed by a set of harmonic functions is obtained, when all factorspaces Mk are Ricciflat. These solutions are generalized to the case of nonRicciflat M0 when also some additional internal Einstein spaces of nonzero curvature are added to M. As an example exact solutions for D 11 supergravity and related 12dimensional theory are presented. |
The Renormalization of the Electroweak Standard Model to All Orders ; We give the renormalization of the standard model of electroweak interactions to all orders of perturbation theory by using the method of algebraic renormalization, which is based on general properties of renormalized perturbation theory and not on a specific regularization scheme. The Green functions of the standard model are uniquely constructed to all orders, if one defines the model by the SlavnovTaylor identity, Wardidentities of rigid symmetry and a specific form of the abelian local gauge Wardidentity, which continues the GellMann Nishijima relation to higher orders. Special attention is directed to the mass diagonalization of massless and massive neutral vectors and ghosts. For obtaining offshell infrared finite expressions it is required to take into account higher order corrections into the functional symmetry operators. It is shown, that the normalization conditions of the onshell schemes are in agreement with the most general symmetry transformations allowed by the algebraic constraints. |
Three Generations in Type I Compactifications ; Generalizing the recent work on threefamily Type I compactifications, we classify perturbative Type I vacua obtained via compactifying on the T6Z2 X Z2 X Z3 orbifold with all possible Wilson lines. In particular, we concentrate on models with gauge groups containing the Standard Model gauge group SU3c X SU2w X U1Y as a subgroup. All of the vacua we obtain contain D5branes and are nonperturbative from the heterotic viewpoint. The models we discuss have threechiral families. We study some of their phenomenological properties, and point out nontrivial problems arising in these models in the phenomenological context. |
On Finite Size Effects in d2 Quantum Gravity ; A systematic investigation is given of finite size effects in d2 quantum gravity or equivalently the theory of dynamically triangulated random surfaces. For Ising models coupled to random surfaces, finite size effects are studied on the one hand by numerical generation of the partition function to arbitrary accuracy by a deterministic calculus, and on the other hand by an analytic theory based on the singularity analysis of the explicit parametric form of the free energy of the corresponding matrix model. Both these reveal that the form of the finite size corrections, not surprisingly, depend on the string susceptibility. For the general case where the parametric form of the matrix model free energy is not explicitly known, it is shown how to perform the singularity analysis. All these considerations also apply to other observables like susceptibility etc. In the case of the Ising model it is shown that the standard Fisherscaling laws are reproduced. |
KadomtsevPetviashvili Hierarchy and Generalized Kontsevich Model ; The review is devoted to the integrable properties of the Generalized Kontsevich Model which is supposed to be an universal matrix model to describe the conformal field theories with c1. It is shown that the deformations of the monomial phase to polynomial one have the natural interpretation in context of socalled equivalent hierarchies. The dynamical transition between equivalent integrable systems is exactly along the flows of the dispersionless KadomtsevPetviashvili hierarchy; the coefficients of the potential are shown to be directly related with the flat quasiclassical times arising in N2 LandauGinzburg topological model. The Virasoro constraint for solution with an arbitrary potential is shown to be a standard Lpconstraint of the equivalent preduced hierarchy with the times additively corrected by the flat coordinates. |
Generalized Hamiltonian Formalism of 21Dimensional NonLinear Model in Polynomial Formulation ; We investigate the canonical structure of the 21dimensional nonlinear sigma model in a polynomial formulation. A current density defined in the nonlinear sigma model is a vector field which satisfies a formal flatness or pure gauge condition. It is the polynomial formulation in which the vector field is regarded as a dynamical variable on which the flatness condition is imposed as a constraint condition by introducing a Lagrange multiplier field. The model so formulated has gauge symmetry under a transformation of the Lagrange multiplier field. We construct the generalized Hamiltonian formalism of the model explicitly by using the Dirac method for constrained systems. We derive three types of the pregaugefixing Hamiltonian systems In the first system, the current algebra is realized as the fundamental Dirac Brackets. The second one manifests the similar canonical structure as the ChernSimons or BF theories. In the last one, there appears an interesting interaction as the dynamical variables are coupled to their conjugate momenta via the covariant derivative. |
Conformal Symmetry and A New Gauge in the Matrix Model ; We generalize the background gauge in the Matrix model to propose a new gauge which is useful for discussing the conformal symmetry. In this gauge, the special conformal transformation SCT as the isometry of the nearhorizon geometry of the Dparticle solution is directly reproduced with the correct coefficient as the quantum correction to the SCT in the Matrix model. We also present a general argument for the relation between the gauge choice and the field redefinition in the Matrix model. |
Fermion dominated composite superstring model and unified description of hadron and lepton degrees of freedom in it ; New string dynamics is formulated on the basis of the extended set of supergauge constraints including not only supergauge Virasoro conditions but also nilpotent supercurrent constraints . This approach arises from a natural generalization of the classical operator manystring vertices. The formulation of this model leads to three twodimensional surfaces for description of hadron strings. It gives some dynamical generalization of ChanPaton factor for string amplitudes in terms of operator vertices. Supersymmetry on the 2d world surface is present but tendimensional supersymmetry is absent. In this approach twodimensional fermion string fields make it possible to give a unified description of hadron and lepton degrees of freedom and of its dynamics. This model allows to solve the problem of elimination of the most part of parity twins in the baryon spectrum. Oneloop and manyloops perhaps amplitudes in this model are finite due to the extended set of supergauge constraints and to the significant excess of the total number of fermion twodimensional fields over the number of boson 2d fields. |
Conformal Blocks and Correlators in WZNW Model. I. Genus Zero ; We consider the free field approach or bosonization technique for the WessZuminoNovikovWitten model with arbitrary KacMoody algebra on Riemann surface of genus zero. This subject was much studied previously, and the paper can be partially taken as a brief survey. The way to obtain wellknown SchechtmanVarchenko solutions of the KnizhnikZamolodchikov equations as certain correlators in free chiral theory is revisited. This gives rise to simple description of space of the WZNW conformal blocks. The general Npoint correlators of the model are constructed from the conformal blocks using nonchiral action for free fields perturbed by exactly marginal terms. The method involved generalizes the DotsenkoFateev prescription for minimal models. As a consequence of this construction we obtain new integral identities. |
Dilatonic formulation for conducting cosmic string models ; It is shown how the the introduction of a suitably defined dilatonic auxiliary field, Phi say, makes it possible for the nonlinear Lagrangian for a generic elastic string model, of the kind appropriate for representing superconducting cosmic strings, to be converted into a standardised form as the sum of a kinetic term that is just homogeneously quadratic in the relevant scalar phase gradient as in a simple linear model together with a potential energy term, V say, that is specified as a generically nonlinear function of Phi. The explicit form of this function is derived for various noteworthy examples, of which the most memorable is that of the transonic string model, as characterised by a given mass scale, m say, for which this potential energy density will be expressible in terms of the zero current limit value Phi0 of Phi by V 1over 2 m bigPhi02 Phi2 Phi02 Phi2 big. |
Brane Universe and Multigravity Modification of gravity at large and small distances ; We consider a modification of gravity at large distances in a Brane Universe which was discussed recently. In these models the modification of gravity at large distances is ultimately connected to existence of negative tension branes and exponentially small tunneling factor. We discuss a general model which interpolates between Bigravity model and GRS model. We also discuss the possible mechanism of stabilization for negative tension branes in AdS background. Finally we show that extra degrees of freedom of massive gravitons do not lead to disastrous contradiction with General Relativity if the stabilization condition int dy sqrtG5 Tmumu2T550 is implemented. |
Brane World Sum Rules ; A set of consistency conditions is derived from Einstein equations for brane world scenarios with a spatially periodic internal space. In particular, the sum of the total tension of the flat branes and the nonnegative integral of the gradient energy of the bulk scalars must vanish. This constraint allows us to make a simple consistency check of several models. We show that the twobrane RandallSundrum model satisfies this constraint, but it does not allow a generalization with smooth branes domain walls, independently of the issue of supersymmetry. The GoldbergerWise model of brane stabilization has to include the backreaction on the metric and the fine tuning of the cosmological constant to satisfy the constraints. We check that this is achieved in the DeWolfeFreedmanGubserKarch scenario. Our constraints are automatically satisfied in supersymmetric brane world models. |
Generalization of the UqglN algebra and staggered models ; We develop a technique of construction of integrable models with a Z2 grading of both the auxiliary chain and quantum time spaces. These models have a staggered disposition of the anisotropy parameter. The corresponding YangBaxter Equations are written down and their solution for the glN case are found. We analyze in details the N2 case and find the corresponding quantum group behind this solution. It can be regarded as quantum Uq,Bgl2 group with a matrix deformation parameter qB with qB2q2. The symmetry behind these models can also be interpreted as the tensor product of the 1Weyl algebra by an extension of UqglN with a Cartan generator related to deformation parameter 1. |
Gauging the Fluid ; A consistent framework has been put forward to quantize the isentropic, compressible and inviscid fluid model in the Hamiltonian framework, using the Clebsch parameterization. The naive quantization is hampered by the noncanonical in particular field dependent Poisson Bracket algebra. To overcome this problem, the BatalinTyutin cite12 quantization formalism is adopted in which the original system is converted to a local gauge theory and is embedded in a it canonical extended phase space. In a different reduced phase space scheme citevy also the original model is converted to a gauge theory and subsequently the two distinct gauge invariant formulations of the fluid model are related explicitly. This strengthens the equivalence between the relativistic membrane where a gauge invariance is manifest and the fluid where the gauge symmetry is hidden. Relativistic generalizations of the extended model is also touched upon. |
Comments on conformal stability of braneworld models ; The stability of 5D braneworld models under conformal perturbations is investigated. The analysis is carried out in the general case and then it is applied to particular solutions. It is shown that models with the Poincare and the de Sitter branes are unstable because they have negative mass squared of gravexcitons whereas models with the Anti de Sitter branes have positive gravexciton mass squared and are stable. It is also shown that 4D effective cosmological and gravitational constants on branes as well as gravexciton masses undergo hierarchy they have different values on different branes. |
On LowEnergy Effective Action of Noncommutative Hypermultiplet Model ; We consider the noncommutative hypermultiplet model within harmonic superspace approach. The 1loop fourpoint contributions to the effective action of selfinteracting qhypermultiplet are computed. This model has two coupling constants instead of a single one in commutative case. It is shown that both these coupling constants are generated by 1loop quantum corrections in the model of qhypermultiplet interacting with vector multiplet. The holomorphic effective action of qhypermultiplet in external gauge superfield is calculated. For the fundamental representation there is no UVIRmixing and the holomorphic potential is a starproduct generalization of a standard commutative one. For the adjoint representation of UN gauge group the leading contributions to the holomorphic effective action are given by the terms respecting for the UVIRmixing which are related to U1 phase of UN group. |
New Critical Matrix Models and Generalized Universality ; We study a class of onematrix models with an action containing nonpolynomial terms. By tuning the coupling constants in the action to criticality we obtain that the eigenvalue density vanishes as an arbitrary real power at the origin, thus defining a new class of multicritical matrix models. The corresponding microscopic scaling law is given and possible applications to the chiral phase transition in QCD are discussed. For generic coupling constants offcriticality we prove that all microscopic correlation functions at the origin of the spectrum remain in the known Bessel universality class. An arbitrary number of Dirac mass terms can be included and the corresponding massive universality is maintained as well. We also investigate the critical behavior at the edge of the spectrum there, in contrast to the behavior at the origin, we find the same critical exponents as derived from matrix models with a polynomial action. |
The Asymptotic Dynamics of twodimensional antide Sitter Gravity ; We show that the asymptotic dynamics of twodimensional de Sitter or antide Sitter JackiwTeitelboim JT gravity is described by a generalized twoparticle CalogeroSutherland model. This correspondence is established by formulating the JT model of AdS gravity in two dimensions as a topological gauge theory, which reduces to a nonlinear 01dimensional sigma model on the boundary of AdS space. The appearance of cyclic coordinates allows then a further reduction to the CalogeroSutherland quantum mechanical model. |
Primordial perturbations in a non singular bouncing universe model ; We construct a simple non singular cosmological model in which the currently observed expansion phase was preceded by a contraction. This is achieved, in the framework of pure general relativity, by means of a radiation fluid and a free scalar field having negative energy. We calculate the power spectrum of the scalar perturbations that are produced in such a bouncing model and find that, under the assumption of initial vacuum state for the quantum field associated with the hydrodynamical perturbation, this leads to a spectral index n1. The matching conditions applying to this bouncing model are derived and shown to be different from those in the case of a sharp transition. We find that if our bounce transition can be smoothly connected to a slowly contracting phase, then the resulting power spectrum will be scale invariant. |
Open string models with ScherkSchwarz SUSY breaking and localized anomalies ; We study examples of chiral fourdimensional IIB orientifolds with ScherkSchwarz supersymmetry breaking, based on freely acting orbifolds. We construct a new Z3xZ3' model, containing only D9branes, and rederive from a more geometric perspective the known Z6'xZ2' model, containing D9, D5 and bar D 5 branes. The cancellation of anomalies in these models is then studied locally in the internal space. These are found to cancel through an interesting generalization of the GreenSchwarz mechanism involving twisted RamondRamond axions and 4forms. The effect of the latter amounts to local counterterms from a lowenergy effective field theory point of view. We also point out that the number of spontaneously broken U1 gauge fields is in general greater than what expected from a fourdimensional analysis of anomalies. |
Massive, Topologically Massive, Models ; In three dimensions, there are two distinct massgenerating mechanisms for gauge fields adding the usual ProcaPauliFierz, or the more esoteric ChernSimons CS, terms. Here we analyze the threeterm models where both types are present, and their various limits. Surprisingly, in the tensor case, these seemingly innocuous systems are physically unacceptable. If the sign of the Einstein term is wrong'' as is in fact required in the CS case, then the excitation masses are always complex; with the usual sign, there is a known region of the two mass parameters where reality is restored, but instead we show that a ghost problem arises, while, for the pure mass'' twoterm system without an Einstein action, complex masses are unavoidable. This contrasts with the smooth behavior of the corresponding vector models. Separately, we show that the partial masslessness'' exhibited by plain massive spin2 models in de Sitter backgrounds is formally shared by the threeterm system it also enjoys a reduced local gauge invariance when this mass parameter is tuned to the cosmological constant. |
Nonperturbative flipped SU5 vacua in heterotic Mtheory ; The evidence for neutrino masses in atmospheric and solar neutrino experiments provides further support for the embedding of the Standard Model fermions in the chiral 16 SO10 representation. Such an embedding is afforded by the realistic free fermionic heteroticstring models. In this paper we advance the study of these string models toward a nonperturbative analysis by generalizing the work of Donagi, Pantev, Ovrut and Waldram from the case of GSU2n1 to GSU2n stable holomorphic vector bundles on elliptically fibered CalabiYau manifolds with fundamental group Z2. We demonstrate existence of GSU4 solutions with three generations and SO10 observable gauge group over Hirzebruch base surface, whereas we show that certain classes of del Pezzo base surface do not admit such solutions. The SO10 symmetry is broken to SU5XU1 by Wilson line. The overlap with the realistic free fermionic heteroticstring models is discussed. |
Exact Standard Model Compactifications from Intersecting Branes ; We construct six stack D6brane vacua nonsupersymmetric that have at low energy exactly the standard model with right handed neutrinos. The construction is based on D6branes intersecting at angles in D 4 type toroidal orientifolds of type I strings. Three U1's become massive through their couplings to RR fields and from the three surviving massless U1's at low energies, one is the standard model hypercharge generator. The two extra massless U1's get broken, as suggested recently hepth0205147, by requiring some intersections to respect N1 supersymmetry thus supporting the appearance of massless charged singlets. Proton and lepton number are gauged symmetries and their anomalies are cancelled through a generalized GreenSchwarz mechanism that gives masses to the corresponding gauge bosons through couplings to RR fields. Thus proton is stable and neutrinos are of Dirac type with small masses as a result of a PQ likesymmetry. The models predict the existence of only two supersymmetric particles, superpartners of nuR's. |
Partition functions of NAHEbased free fermionic string models ; The heterotic string free fermionic formulation produced a large class of three generation models, with an underlying SO10 GUT symmetry which is broken directly at the string level by Wilson lines. A common subset of boundary condition basis vectors in these models is the NAHE set, which corresponds to Z2 X Z2 orbifold of an SO12 Narain lattice, with h11,h2127,3. Alternatively, a manifold with the same data is obtained by starting with a Z2 X Z2 orbifold at a generic point on the lattice, with h11,h2151,3, and adding a freely acting Z2 involution. The equivalence of the two constructions is proven by examining the relevant partition functions. The explicit realization of the shift that reproduces the compactification at the free fermionic point is found. It is shown that other closely related shifts reproduce the same massless spectrum, but different massive spectrum, thus demonstrating the utility of extracting information from the full partition function. A freely acting involution of the type discussed here, enables the use of Wilson lines to break the GUT symmetry and can be utilized in nonperturbative studies of the free fermionic models. |
NC Effective Gauge Model for Multilayer FQH States ; We develop an effective field model for describing FQH states with rational filling factors that are not of Laughlin type. These kinds of systems, which concern single layer hierarchical states and multilayer ones, were observed experimentally; but have not yet a satisfactory non commutative effective field description like in the case of Susskind model. Using D brane analysis and fiber bundle techniques, we first classify such states in terms of representations characterized, amongst others, by the filling factor of the layers; but also by proper subgroups of the underlying Un gauge symmetry. Multilayer states in the lowest Landau level are interpreted in terms of systems of D2 branes; but hierarchical ones are realized as Fiber bundles on D2 which we construct explicitly. In this picture, Jain and Haldane series are recovered as special cases and have a remarkable interpretation in terms of Fiber bundles with specific intersection matrices. We also derive the general NC commutative effective field and matrix models for FQH states, extending Susskind theory, and give the general expression of the rational filling factors as well as their non abelian gauge symmetries. |
N1 Supersymmetry, Deconstruction, and Bosonic Gauge Theories ; We show how the full holomorphic geometry of local CalabiYau threefold compactifications with N1 supersymmetry can be obtained from matrix models. In particular for the conifold geometry we relate Fterms to the general amplitudes of c1 noncritical bosonic string theory, and express them in a quiver or, equivalently, super matrix model. Moreover we relate, by deconstruction, the uncompactified c1 theory to the sixdimensional conformal 2,0 theory. Furthermore, we show how we can use the idea of deconstruction to connect 4k dimensional supersymmetric gauge theories to a kdimensional internal bosonic gauge theory, generalizing the relation between 4d theories and matrix models. Examples of such bosonic systems include unitary matrix models and gauged matrix quantum mechanics, which deconstruct 5dimensional supersymmetric gauge theories, and ChernSimons gauge theories, which deconstruct gauge theories living on branes wrapped over cycles in CalabiYau threefolds. |
Interacting families of Calogerotype particles and SU1,1 algebra ; We study a onedimensional model with F interacting families of Calogerotype particles. The model includes harmonic, twobody and threebody interactions. We emphasize the universal SU1,1 structure of the model. We show how SU1,1 generators for the whole system are composed of SU1,1 generators of arbitrary subsystems. We find the exact eigenenergies corresponding to a class of the exact eigenstates of the Ffamily model. By imposing the conditions for the absence of the threebody interaction, we find certain relations between the coupling constants. Finally, we establish some relations of equivalence between two systems containing F families of Calogerotype particles. |
Yukawa Coupling Structure in Intersecting Dbrane Models ; The structure of Yukawa coupling matrices is investigated in type IIA T6Z2 x Z2 orientifold models with intersecting Dbranes. Yukawa coupling matrices are difficult to be realistic in the conventional models in which the generation structure emerges by the multiple intersection of Dbranes in the factorized T6 T2 x T2 x T2. We study the new type of flavor structure, where Yukawa couplings are dynamically generated, and show this type of models lead to nontrivial structures of Yukawa coupling matrices, which can be realistic. |
Mirror symmetry for topological sigma models with generalized Kahler geometry ; We consider topological sigma models with generalized Kahler target spaces. The mirror map is constructed explicitly for a special class of target spaces and the topological A and B model are shown to be mirror pairs in the sense that the observables, the instantons and the anomalies are mapped to each other. We also apply the construction to open topological models and show that A branes are mapped to B branes. Furthermore, we demonstrate a relation between the field strength on the brane and a twovector on the mirror manifold. |
A Knot Model Sugugested by the Standard Electroweak Theory ; We attempt to go beyond the standard electroweak theory by replacing SU2 with its qdeformation SUq2. This step introduces new degrees of freedom that we interpret as indicative of nonlocality and as a possible basis for a solitonic model of the elementary particles. The solitons are conjectured to be knotted flux tubes labelled by the irreducible representations of SUq2, an alglebra which is not only closely related to the standard theory but also plays an underlying role in the description of knots. Each of the four families of elementary fermions is conjectured to be represented by one of the four possible trefoils. The three individual fermions belonging to any family are then assumed to occupy the three lowest states in the excitation spectrum of the local trefoil for that family. One finds a not unreasonable variation of q among the lepton and quark families. The model in its present form predicts a fourth generation of fermions as well as a neutrino mass spectrum. The model may be refined depending on whether or not the fourth generation is found. |
Photon as a Vector Goldstone Boson Nonlinear Model for QED ; We show that QED in the Coulomb gauge can be considered as a low energy linear approximation of a nonlinear sigma type model where the photon emerges as a vector Goldstone boson related to the spontaneous breakdown of Lorentz symmetry down to its spatial rotation subgroup at some high scale M. Starting with a general massive vector field theory one naturally arrives at this model if the pure spin1 value for the vector field Amux provided by the Lorentz condition partialmuAmux0 is required. The model coincides with conventional QED in the Coulomb gauge in the limit of M going to infinity and generates a very particular form for the Lorentz and CPT symmetry breaking terms, which are suppressed by powers of M. |
Cosmic Acceleration and the String Coupling ; In the context of a cosmological string model describing the propagation of strings in a timedependent RobertsonWalker background spacetime, we show that the asymptotic acceleration of the Universe can be identified with the square of the string coupling. This allows for a direct measurement of the tendimensional string coupling using cosmological data. We conjecture that this is a generic feature of a class of noncritical string models that approach asymptotically a conformal critical sigma model whose target space is a fourdimensional spacetime with a dilaton background that is linear in sigmamodel time. The relation between the cosmic acceleration and the string coupling does not apply in critical strings with constant dilaton fields in four dimensions. |
On covariant longdistance modifications of Einstein theory and strong coupling problem ; We present generic form of the covariant nonlocal action for infrared modifications of Einstein theory recently suggested within the weakfield curvature expansion. In the lowest order it is determined by two nonlocal operators kernels of Ricci tensor and scalar quadratic forms. In models with a low strongcoupling scale this action also incorporates the strongly coupled mode which cannot be perturbatively integrated out in terms of the metric field. This mode enters the action as a Lagrange multiplier for the constraint on metric variables which reduces to the curvature scalar and enforces the latter to vanish on shell. Generic structure of the action is demonstrated on the examples of the FierzPauli and DvaliGabadadzePorrati models and their extensions. The gaugedependence status of the strongcoupling and VDVZ problems is briefly discussed along with the manifestly gaugeinvariant formalism of handling the braneworld gravitational models at classical and quantum levels. |