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.
120235525
Some New Features in the Pseudoscalar Meson and Vector Meson Photoproductions
We investigate the role of the t-channel meson exchange in various photoproduction processes to discuss features of the respective production mechanism. For the less model-dependent analysis we work with the t-channel meson pole reggeized in the Born approximation amplitude. With the meson–baryon coupling constants chosen consistently with symmetry prediction we show that the Reggeized pole model could reproduce the experimental data to a good degree in the lower energy region. Numerical consequences show the significance of the tensor meson exchange in the γp → K+Λ, the dominance of the pseudoscalar meson exchange in the πΔ (and KΣ*) processes, and the sizable role of the vector-meson magnetic moment in the charged ρ (and K*) photoproductions, respectively. These new features from the present analyses could provide a useful guide for future study of the N* resonances in the low energy region.
119181837
Axial charges of the nucleon and N* resonances
The axial charges of the nucleon and the well-established N * resonances are studied within a consistent framework. For the first time the axial charges of the N * resonances are produced for the relativistic constituent quark model. The axial charge of the nucleon is predicted close to experiment, and the ones of N * (1535) and N * (1650), the only cases where such a comparison is possible, agree well with results from quantum chromodynamics on the lattice that have recently become available. The relevance of the magnitudes of the N * axial charges for the low-energy behavior of quantum chromodynamics is discussed.
56153539
Quark-Model Predictions for Axial Charges of Nucleon and N* Resonances
We have investigated the axial charges of the nucleon and N ∗ resonances in a relativistic framework. Besides the axial charge of the nucleon, first predictions are reported for the axial charges of all well-established N ∗ resonances below∼1.9 GeV as produced by the relativistic constituent quark models relying on Goldstone- boson-exchange and one-gluon-exchange hyperfine interactions. The results for the axial charge of the nucleon are found close to experiment but with somewhat smaller values, similar to modern findings from quantum chromodynamics on the lattice. The predictions of the axial charges of the negative-parity N ∗ (1535) and N ∗ (1650) resonances also agree with what has most recently become available from lattice calculations. We discuss the roles of the axial charges of the N ∗ resonances for the phenomenon of chiral-symmetry restoration possibly occurring in the higher hadron spectra.
125677314
Unified model for light- and heavy-flavor baryon resonances
120248095
Axial Properties of Baryon Ground and Resonant States
We report results from a study of axial charges of baryon ground and resonant states with relativistic constituent quark models. In particular, we consider the axial charges of the octet and decuplet baryons N, Σ, Ξ, Δ, Σ*, and Ξ*. The theoretical predictions are compared to experiment, in the case of the N, and to results from other approaches, especially from lattice quantum chromodynamics and chiral perturbation theory. Some remarks are also made regarding the role of axial charges for spontaneous breaking of chiral symmetry.
13840314
Determining Reheating Temperature at LHC with Axino or Gravitino Dark Matter
After a period of inflationary expansion, the Universe reheated and reached full thermal equilibrium at the reheating temperature TR. In this talk, based on [1], we point out that, in the context of effective low‐energy supersymmetric models, LHC measurements may allow one to determine TR as a function of the mass of the dark matter particle assumed to be either an axino or a gravitino. An upper bound on their mass and on TR may also be derived.
118444511
Indirect detection of gravitino dark matter including its three-body decays
It was recently pointed out that in supersymmetric scenarios with gravitino dark matter and bilinear R-parity violation, gravitinos with masses below MW typically decay with a sizable branching ratio into the 3-body final states W*? and Z*?. In this paper we study the indirect detection signatures of gravitino dark matter including such final states. First, we obtain the gamma ray spectrum from gravitino decays, which features a monochromatic contribution from the decay into ?? and a continuum contribution from the three-body decays. After studying its dependence on supersymmetric parameters, we compute the expected gamma ray fluxes and derive new constraints, from recent FERMI data, on the R-parity breaking parameter and on the gravitino lifetime. Indirect detection via antimatter searches, a new possibility brought about by the three-body final states, is also analyzed. For models compatible with the gamma ray observations, the positron signal is found to be negligible whereas the antiproton one can be significant.
15628636
Multiple scalar particle decays and perturbation generation
We study the evolution of the universe which contains multiple non-relativistic scalar fields decaying into both radiation and pressureless matter. We present a powerful analytic formalism for calculating the matter and radiation curvature perturbations, and find that our analytic estimates agree with full numerical results within an error of less than one per cent. Also we discuss the isocurvature perturbation of matter and radiation components, which may be detected by near future cosmological observations, and point out that it crucially depends on the branching ratio of the decay rate of the scalar fields and that it is hard to make any model independent predictions.
16283086
Three generation magnetized orbifold models
Abstract We study three generation models in the four-dimensional spacetime, which can be derived from the ten-dimensional N = 1 super-Yang–Mills theory on the orbifold background with a non-vanishing magnetic flux. We classify the flavor structures and show possible patterns of Yukawa matrices. Some examples of numerical studies are also shown.
18667052
A re-analysis of gravitino dark matter in the constrained MSSM
We re-consider the gravitino as dark matter in the framework of the Constrained MSSM. We include several recently suggested improvements on: (i) the thermal production of gravitinos, (ii) the calculation of the hadronic spectrum from NLSP decay and (iii) the BBN calculation including stau bound-state effects. In most cases we find an upper bound on the reheating temperature TR a few × 107GeV from over-production of 6Li from bound state effects. We also find an upper limit on the stau lifetime of 3 × 104sec, which is nearly an order of magnitude larger than the simple limit 5 × 103sec often used to avoid the effect of bound-state catalysis. The bound on TR is relaxed to a few × 108GeV when we use a more conservative bound on 6Li/7Li, in which case a new region at small stau mass at ~ 100GeV and much longer lifetimes opens up. Such a low stau mass region can be easily tested at the LHC.