203614509
Ju n 20 08 Production of the charged Higgs bosons at the CERN Large Hadron Collider in the left-right symmetric model
Search of Higgs bosons is the primary goal of the CERN Large Hadron Collider (LHC). In the standard model (SM), one neutral Higgs boson exists as a result of the electroweak symmetry breaking (EWSB), of which mass is not predicted in the theoretical framework. The discovery potential for the SM Higgs boson at the LHC will reach to about 1 TeV with the integrated luminosity of 100 fb. It implies that the SM Higgs boson will be discovered at the LHC at more than 5-σ level. In many models of new physics beyond the SM, however, more symmetries are involved and the Higgs sector should be extended to break larger symmetry. Signatures of an extended Higgs sector would provide direct evidence for new physics beyond the SM. Models with an extended Higgs sector often contain charged Higgs bosons H, which do not exist within the SM. The two Higgs doublet model (2HD) is one of the simplest extension of the SM and the Higgs structure of the minimal supersymmetric standard model (MSSM). There are three neutral Higgs bosons, h, H, A and a pair of charged Higgs bosons H in the 2HD model and the MSSM. Hereafter the 2HD model and the MSSM are just called the 2HD model generically. If the H bosons are lighter than the top quark, they can be produced in the top quark decay processes t → bH. Search for H from top quark decays in the 2HD model has been performed at Tevatron and no evidence for H production is found [1]. The CERN Large Electron Positron Collider (LEP) has also examined the charged Higgs bosons up to √ s = 200 GeV through the pair production of H to present the lower bound of the charged Higgs boson mass [2, 3]. Recent measurement of Br(B → τν) by Belle provides indirect constraints on the charged Higgs bosons in the 2HD model via the annihilation diagram mediated by H boson [4, 5]. The absence of the observed charged Higgs boson so far derives constraints on (tanβ,mH±) parameter space for the 2HD model. If the charged Higgs bosons are heavier than the top quark, we have to observe the direct production at hadron colliders. The most promising channel for the charged Higgs boson production at the LHC is the gb → tH process which has been extensively studied [6, 7, 8, 9]. The Drell-Yan mechanism gg, qq̄ → HH and the associated production with a W boson, qq̄ → HW are suppressed due to the weak couplings, low quark luminosity, and loop suppression. The discovery potential of the H bosons at the LHC has been studied by ATLAS [10] and CMS [11] groups. Expected to be discovered is a MSSM charged Higgs boson as heavy as 1 TeV at the 5-σ confidence level, or may be excluded up to the mass of 1.5 TeV at 95 % C.L. at the LHC with the MSSM radiative corrections [9]. The left-right (LR) symmetric model based on the gauge symmetry, SU(2)L× SU(2)R× U(1)B−L, usually contain a bidoublet Higgs field φ(2, 2̄, 0) for the EWSB and the Yukawa couplings represented by
15426025
Large extra dimension effects on the spin configuration of the top quark pair at e + e − colliders
Large extra dimension effects on the spin configuration of the top quark pair at the ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}t\overline{t}$ process are studied. It is shown that the TeV scale quantum gravity effects cause significant deviations from standard model (SM) predictions for the spin configuration in the off-diagonal basis: they lead to substantial cross sections of the like-spin states of the top quark pair, which vanish in the SM; they weaken the pure dominance of the processes, the up-down (down-up) spin states for the left-handed (right-handed) beam. In addition it is shown that the angular cut $\ensuremath{-}0.5l\mathrm{cos}\ensuremath{\theta}l0$ is very effective to determine the sign of the quantum gravity corrections.
17539215
Implications of the recent CERN LEP data on nonuniversal interactions with the precision electroweak tests
We explore the nonuniversal interaction effects in terms of the precision variables epsilons with the recent CERN LEP data reported by the Electroweak Working Group. The epsilon variables with the nonuniversal interactions are calculated and constrained by the experimental ellipses in the {epsilon}{sub 1}{endash}{epsilon}{sub b}, {epsilon}{sub 2}{endash}{epsilon}{sub b}, and {epsilon}{sub 3}{endash}{epsilon}{sub b} planes. We find that the new data enable us to make a stringent test on the correction to Z{r_arrow}b{bar b} vertex. The {epsilon}{sub b} variable is sensitive to the Zb{bar b} couplings and thus plays a major role to give constraints on the nonuniversal interaction effects. Upon imposing the new data on {epsilon}{sub b}, we have the allowed range of the model parameter {kappa}{sub L}=0.0063{plus_minus}0.0030 at 1-{sigma} level with m{sub t}=175 GeV. Along with the minimal contact term, we predict the new physics scale {Lambda}{approximately} 1.6 TeV. By combining the experimental results from all planes we obtain the allowed range of {kappa}{sub L}: 0.003{lt}{kappa}{sub L}{lt}0.010 at 95{percent} C.L. {copyright} {ital 1997} {ital The American Physical Society}
16963420
Evolution equation for the heavy quark distribution function in the parton model approach
We explore the perturbative QCD corrections to the inclusive semileptonic decays of $B$ mesons. In inclusive $B$ decay processes the parton picture works well and the scaling feature manifests because the mass of $b$ quark is larger than the QCD scale. Due to this property, the decay rate may be expressed by a single structure function describing the light-cone distribution of $b$ quark apart from the kinematic factor. We derive a $q^2$ evolution equation for the distribution function, which violates the scaling property through the Altarelli-Parisi type approach. The evolution equation is numerically solved and its phenomenological implications are also discussed.
16221979
POLARIZATION EFFECTS ON THE E+E- W+W- PROCESS WITH LARGE EXTRA DIMENSIONS
Abstract We study large extra dimension effects on the polarizations of the W pair and electron beam at the e + e − → W + W − process. It is shown that the measurements of the cross section for transversely polarized W pair with the right-handed electron beam remarkably enhance the possibilities to see the low scale quantum gravity effects. Higher Linear Collider bounds on the string scale in this model can be obtained by using the left-handed electron beam.
14611917
Polarization effects on W boson pair productions with the extra neutral gauge boson at the e^+ e^- Linear Collider
We perform the comprehensive analysis of the polarization effects on the e^+e^- -> W^+W^- process in the presence of the extra neutral gauge boson at the LC energies. Consideration of the polarizations of the produced W bosons and the beam polarizations provides substantial enhancements of the sensitivity to the Z-Z' mixing angles in various models and the asymmetry variables also give the strict constraints on the mixing angles. We find that the \chi-model and the left-right model get the strict constraint from \sigma_{LL}^{unpol} while the \psi-model and the \eta-model from the beam polarization asymmetry.
12063647
Vortex string dynamics in an external antisymmetric tensor field
Abstract We study the Lund–Regge equation that governs the motion of strings in a constant background antisymmetric tensor field by using the duality between the Lund–Regge equation and the complex sine-Gordon equation. Similar to the cases of vortex filament configurations in fluid dynamics, we find various exact solitonic string configurations which are the analogue of the Kelvin wave, the Hasimoto soliton and the smoke ring. In particular, using the duality relation, we obtain a completely new type of configuration which corresponds to the breather of the complex sine-Gordon equation.
18455496
Deformed Matrix Theories with N=8 and Fivebranes in the PP Wave Background
M(atrix) theory is known to be mass-deformed in the pp-wave background and still retains all 16 dynamical supersymmetries. We consider generalization of such deformations on super Yang-Mills quantum mechanics (SYQM) with less supersymmetry. In particular this includes = 8 U(N) SYQM with a single adjoint and any number of fundamental hypermultiplets, which is a pp-wave deformation of DLCQ matrix theory of fivebranes. With k ≥ 1 fivebranes, we show that a rich vacuum structure exists, with many continuous family of solutions that preserve all dynamical supersymmetries. The vacuum moduli space contains copies of CPk−1 of various sizes.
122069269
Ground state of high-density matter
Abstract It is shown that if an upper bound to the false vacuum energy of the electroweak Higgs potential is satisfied, the true ground state of high-density matter is not nuclear matter, or even strange-quark matter, but rather a non-topological soliton where the electroweak symmetry is exact and the fermions are massless. We examine this possibility in the standard SU(3) C ⊗ SU(2) L ⊗ U(1) Y model. The bound to the false vacuum energy is satisfied only for a narrow range of the Higgs boson masses in the minimal electroweak model (within a few eV of its minimum allowed value of 6.6 GeV), and a somewhat wider range for electroweak models with a non-minimal Higgs sector.
8741649
Topological Twisting of Multiple M2-brane Theory
Bagger-Lambert-Gustavsson theory with infinite dimensional gauge group has been suggested to describe M5-brane as a condensation of multiple M2-branes. Here we perform a topological twisting of the Bagger-Lambert-Gustavsson theory. The original SO(8) R-symmetry is broken to SO(3) × SO(5), where the former may be interpreted as a diagonal subgroup of the Euclidean M5-brane world-volume symmetry SO(6), while the latter is the isometry of the transverse five directions. Accordingly the resulting action contains an one-form and five scalars as for the bosonic dynamical fields. We further lift the action to a generic curved three manifold. In order to make sure the genuine topological invariance, we construct an off-shell supersymmetric formalism such that the scalar supersymmetry transformations are nilpotent strictly off-shell and independent of the metric of the three manifold. The one loop partition function around a trivial background yields the Ray-Singer torsion. The BPS equation involves an M2-brane charge density given by a Nambu-Goto action defined in an internal three-manifold.
119309124
Ramond-Ramond cohomology and O(D, D) T-duality
A bstractIn the name of supersymmetric double field theory, superstring effective actions can be reformulated into simple forms. They feature a pair of vielbeins corresponding to the same spacetime metric, and hence enjoy double local Lorentz symmetries. In a manifestly covariant manner — with regard to O(D, D) T-duality, diffeomorphism, B-field gauge symmetry and the pair of local Lorentz symmetries — we incorporate R-R potentials into double field theory. We take them as a single object which is in a bi-fundamental spinorial representation of the double Lorentz groups. We identify cohomological structure relevant to the field strength. A priori, the R-R sector as well as all the fermions are O(D, D) singlet. Yet, gauge fixing the two vielbeins equal to each other modifies the O(D, D) transformation rule to call for a compensating local Lorentz rotation, such that the R-R potential may turn into an O(D, D) spinor and T-duality can flip the chirality exchanging type IIA and IIB supergravities.