252 research outputs found
Implications of the measurements of B_s - B_s bar mixing on SUSY models
We derive constraints on the mass insertion parameters from the recent
measurements of B_s - B_s bar mixing, and discuss their implications on SUSY
breaking mediation mechanisms and SUSY flavor models. Some SUSY flavor models
are already excluded or disfavored by B_s - B_s bar mixing. We also discuss how
to test the SM and SUSY models in the future experiments, by studying other CP
violating observables related to b -> s transition, such as the time-dependent
CP asymmetry in B -> phi K_S and the direct CP asymmetry in B -> X_s gamma.Comment: 29 page
Sflavor mixing map viewed from a high scale in supersymmetric SU(5)
We study flavor violation in a supersymmetric SU(5) grand unification
scenario in a model-independent way employing mass insertions. We examine how
the quark and the lepton sector observables restrict sfermion mixings. With a
low soft scalar mass, a lepton flavor violating process provides a stringent
constraint on the flavor structure of right-handed down-type squarks. In
particular, mu -> e gamma turns out to be highly susceptible to the 1-3 and 2-3
mixings thereof, due to the radiative correction from the top Yukawa coupling
to the scalar mass terms of 10. With a higher scalar mass around the optimal
value, in contrast, the quark sector inputs such as B-meson mixings and hadron
electric dipole moment, essentially determine the room for sfermion mixing. We
also discuss the recent deviation observed in B_s mixing phase, projected
sensitivity of forthcoming experiments, and ways to maintain the power of
leptonic restrictions even after incorporating a solution to fix the incorrect
quark-lepton mass relations.Comment: 40 pages, updated using phi_s from HFAG, conclusion unchange
B0 - B0 bar mixing, B -> J/psi K_S and B -> X_d gamma in general MSSM
We consider the gluino-mediated SUSY contributions to B0 - B0 bar mixing, B
-> J/psi K_S and B -> X_d gamma in the mass insertion approximation. We find
the LL mixing parameter can be as large as |delta_{13}^d_{LL}| < 2*10^-1, but
the LR mixing is strongly constrained by the B -> X_d gamma branching ratio and
we find |delta_{13}^d_{LR}| < 10^-2. The implications for the direct CP
asymmetry in B -> X_d gamma and the dilepton charge asymmetry (A_{ll}) are also
discussed, where substantial deviations from the standard model predictions are
possible.Comment: 14 pages, 4 figure
Chiral perturbation theory for pentaquark baryons and its applications
We construct a chiral lagrangian for pentaquark baryons assuming that the
recently found Theta^+ (1540) state belongs to an antidecuplet of SU(3) flavor
symmetry with J^P = (1/2)^(+-). We derive the Gell-Mann-Okubo formulae for the
antidecuplet baryon masses, and a possible mixing between the antidecuplet and
the pentaquark octet. Then we calculate the cross sections for pi^- p -> K^-
Theta^+ and gamma n -> K^- Theta^+ using our chiral lagrangian. The resulting
amplitudes respect the underlying chiral symmetry of QCD correctly. We also
describe how to include the light vector mesons in the chiral lagrangian.Comment: 4 page
Lepton masses and mixing angles from heterotic orbifold models
We systematically study the possibility for realizing realistic values of
lepton mass ratios and mixing angles by using only renormalizable Yukawa
couplings derived from heterotic -I orbifold. We assume one pair of up and
down sector Higgs fields. We consider both the Dirac neutrino mass scenario and
the seesaw scenario with degenerate right-handed majorana neutrino masses. It
is found that realistic values of the charged lepton mass ratios,
and , the neutrino mass squared difference ratio, , and the lepton mixing angles can be obtained in
certain cases.Comment: 22 pages, late
Supernova Axion Emissivity with Resonance in Heavy Baryon Chiral Perturbation Theory
In this paper, we evaluate the energy loss rate of supernovae induced by the
axion emission process with the resonance
in the heavy baryon chiral perturbation theory for the first time. Given the
axion-nucleon- interactions, we include the previously ignored
-mediated graphs to the process. In particular,
the -mediated diagram can give a resonance contribution to the
supernova axion emission rate when the center-of-mass energy of the pion and
proton approaches the mass. With these new contributions, we
find that for the typical supernova temperatures, compared with the earlier
work with the axion-nucleon (and axion-pion-nucleon contact) interactions, the
supernova axion emissivity can be enhanced by a factor of 4(2) in the
Kim-Shifman-Vainshtein-Zakharov model and up to a factor of 5(2) in the
Dine-Fischler-Srednicki-Zhitnitsky model with small values.
Remarkably, we notice that the resonance gives a destructive
contribution to the supernova axion emission rate at high supernova
temperatures, which is a nontrivial result in this study.Comment: 17 pages, 4 figures, typo is fixed, references updated. Matches
version published in Physical Review
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