118998046
Flavor analysis of nucleon electromagnetic form factors
We have performed an evaluation of the individual up- and down-flavor contributions to the nucleon electromagnetic form factors within a relativistic constituent-quark model. It is found that the theoretical parameter-free predictions agree surprisingly well with recent experimental data from a flavor decomposition of the proton and neutron electromagnetic form factors for momentum transfers up to $Q^2\sim\;$3.5 GeV$^2$. It means that in this regime three-quark valence degrees of freedom dominate and other contributions, such as explicit mesonic effects, can at most play a minor role.
119691200
Spectroscopy of Baryons as Relativistic Three-Quark Systems
We present results from a study of baryon spectral properties within a relativistic constituent-quark model. In particular, we demonstrate the performance of a universal quark model for all light-, strange-, and heavy-flavor baryons with regard to their spectroscopy. Thereby we produce insights into the effective interaction between constituent quarks of the various flavors up, down, strange, charm, and bottom. The relativistically invariant mass spectra are obtained by two different methods for calculating the microscopic three-quark systems: a stochastic variational method, solving the eigenvalue problem of the invariant mass operator expressed by differential equations, and a Faddeev integral-equation method, adapted to treating long-range interactions, such as the quark confinement. The corresponding results agree very well, generally within a few percents. Taking into account relativistic effects through Poincaré invariance of the mass operator, or equivalently of the Hamiltonian, turns out to be of utmost importance.
126277985
Relativistic quark-model spectroscopy of light and heavy baryons
We report results from a study of lightand heavy-baryon spectra within a relativistic constituent quark model that relies on a universal dynamics for baryons of all flavor contents. The (linear) confinement is taken according to the string tension of quantum chromodynamics and the (flavordependent) hyperfine interaction is derived from an effective Lagrangian resulting from chiralsymmetry breaking. Here, we specifically show results for all baryons that are included in the phenomenological data base of the Particle Data Group with at least three-star status. In general, the spectra are reproduced in good agreement with experiment for both ground and excited states.
118574536
Universal Constituent-Quark Model for Baryons
We present a relativistic constituent-quark model that covers all known baryons from the nucleon up to bbb. The corresponding invariant mass operator includes a linear connement and a hyperne interaction based on eective degrees of freedom. The model provides for a unied description of practically all baryon spectra in good agreement with present phenomenology and it can tentatively be employed for the relativistic treatment of all kinds of baryon reactions. Predictions of states still missing in the phenomenological data base, especially in the lesser explored heavy-avor sectors of charm and bottom baryons, should be important especially for future experiments in these areas.
118129565
Axial properties of the nucleon and N* resonances
We report results from a theoretical study of axial charges and axial form factors of the nucleon N and its resonant states N*. By employing relativistic constituent-quark models we could produce for the first time covariant predictions for the axial-current matrix elements. The calculations are performed in the point form of Poincare-invariant quantum mechanics. The axial charge as well as the axial form factor of the nucleon are reproduced close to phenomenology. The axial charges of the N*(1535) and N*(1650) resonances – the only cases where such a comparison is possible – agree well with results from quantum chromodynamics on the lattice that have recently become available. Here, we present the axial charges of all N* excitations below ~2 GeV and two examples of N* axial form factors. These results should be interesting for comparison with other approaches, especially with regard to the issue of chiral-symmetry restoration in higher-lying hadron resonances.
125677314
Unified model for light- and heavy-flavor baryon resonances
118554240
Contorted flavors in grand unification and proton decay
Abstract Conventionally we collect electron and up/down quarks ( u , d ) ⊕ ( ν e , e ) to form unified generations, and collect the left-handed and the right-handed fermions of the same flavors ( ν e , e ) ⊕ e ¯ . We can alternatively have a contorted multiplet, made by pairing different quarks and leptons, like ( u , d ) ⊕ ( ν μ , μ ) or ( u , d ) ⊕ ( ν τ , τ ) , and/or between different left- and right-handed fermions to ( ν e , e ) ⊕ μ ¯ , etc. These can suppress proton decay, due to its high flavor dependence, while having the correct fermion masses.
92983543
Dark matter, {mu} problem, and neutrino mass with gauged R symmetry
We show that the {mu} problem and the strong CP problem can be resolved in the context of the gauged U(1){sub R} symmetry, realizing an automatic Peccei-Quinn symmetry. In this scheme, right-handed neutrinos can be introduced to explain small Majorana or Dirac neutrino mass. The U(1){sub R} D-term mediated supersymmetry (SUSY) breaking, called the U(1){sub R} mediation, gives rise to a specific form of the flavor-conserving superpartner masses. For the given solution to the {mu} problem, electroweak symmetry breaking condition requires the superpartners of the standard model at low energy to be much heavier than the gravitino. Thus, the dark matter candidate can be either gravitino or right-handed sneutrino. In the Majorana neutrino case, only gravitino is a natural dark matter candidate. On the other hand, in the Dirac neutrino case, the right-handed sneutrino can be also a dark matter candidate as it gets mass only from SUSY breaking. We discuss the non-thermal production of our dark matter candidates from the late decay of stau and find that the constraints from the big bang nucleosynthesis can be evaded for a TeV-scale stau mass.
54193494
Sparticle spectrum of large volume compactification
We examine the large volume compactification of Type IIB string theory or its F theory limit and the associated supersymmetry breakdown and soft terms. It is crucial to incorporate the loop-induced moduli mixing, originating from radiative corrections to the Kähler potential. We show that in the presence of moduli mixing, soft scalar masses generically receive a D-term contribution of the order of the gravitino mass m3/2 when the visible sector cycle is stabilized by the D-term potential of an anomalous U(1) gauge symmetry, while the moduli-mediated gaugino masses and A-parameters tend to be of the order of m3/2/8π2. It is noticed also that a too large moduli mixing can destabilize the large volume solution by making it a saddle point.
118615227
Analysis of techni-dilaton as a dark matter candidate
A bstractThe almost conformal dynamics of walking technicolor (TC) implies the existence of the approximate scale invariance, which breaks down spontaneously by the condensation of anti-techni and techni-fermions. According to the Goldstone theorem, a spinless, parity-even particle, called techni-dilaton (TD), then emerges at low energy. If TC exhibits an extreme walking, TD mass, MTD, is parametrically much smaller than that of techni-fermions (~1 TeV), while its decay constant is comparable to the cutoff scale of walking TC. We analyze the light, decoupled TD as a dark matter candidate and study cosmological productions of TD, both thermal and non-thermal, in the early Universe. The thermal population is governed dominantly by single TD production processes involving vertices breaking the scale symmetry, while the non-thermal population is by the vacuum misalignment and is accumulated via harmonic and coherent oscillations of misaligned classical TD fields. The non-thermal population turns out to be dominant and large enough to explain the abundance of presently observed dark matter, while the thermal population is highly suppressed due to the large TD decay constant. Several cosmological and astrophysical limits on the light, decoupled TD are examined to find that the mass MTD is constrained to be in a range, 0.01eV ≲ MTD ≲ 500 eV. From the combined constraints on cosmological productions and astrophysical observations, we find that the light, decoupled TD can be a good dark matter candidate with the mass around a few hundreds of eV for typical models of (extreme) walking TC. We finally mention possible designated experiments to detect the TD dark matter.
119250759
Flavor structure from magnetic fluxes and non-Abelian Wilson lines
We study the flavor structure of four-dimensional (4D) effective theories, which are derived from extra dimensional theories with magnetic fluxes and non-Abelian Wilson lines. We study zero-mode wave functions in generic case and compute Yukawa couplings as well as four-point couplings. In our models, we also discuss non-Abelian discrete flavor symmetries such as ${D}_{4}$, $\ensuremath{\Delta}(27)$, and $\ensuremath{\Delta}(54)$. The orbifold background is also studied.