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Kentaro Kojima

Publications and source records attributed to Kentaro Kojima.

20 records · Page 2Linked to original sources

Low-energy Variety of Asymmetric SUSY Flavor Structure

In this letter we study the low-energy phenomenology and cosmological implications of supersymmetric grand unified theory with asymmetric flavor structure, which is suggested by the recent observation of fermion masses and mixing angles. The predictions of the scenario are rather dependent on a Yukawa parameter fixed by group-theoretical argument. A reduced value of the parameter gives a resolution to the sign problem of supersymmetric Higgs mass μ, with which the theory becomes simultaneously consistent with the experimental data of bottom/tau mass ratio, flavor-changing rare decay of bottom quark, and the muon anomalous magnetic moment. The relic abundance of the lightest superparticle as cold dark matter of the universe is also investigated in light of the three-years WMAP result. A new source of flavor violation is found in the D-term induced scalar masses, that is a distinctive signature of the generation asymmetry.

hep-ph↗

Neutrino-induced Electroweak Symmetry Breaking in Supersymmetric SO(10) Unification

The radiative electroweak symmetry breaking, the unification of third-generation Yukawa couplings, and flavor-changing rare decay are investigated in two types of supersymmetric SO(10) scenarios taking into account of the effects of neutrino physics, i.e. the observed large generation mixing and tiny mass scale. The first scenario is minimal, including right-handed neutrinos at intermediate scale with the unification of third-generation Yukawa couplings. Another is the case that the large mixing of atmospheric neutrinos originates from the charged-lepton sector. Under the SO(10)-motivated boundary conditions for supersymmetry-breaking parameters, typical low-energy particle spectrum is discussed and the parameter space is identified which satisfies the conditions for successful radiative electroweak symmetry breaking and the experimental mass bounds of superparticles. In particular, the predictions of the bottom quark mass and the b \to s gamma branching ratio are fully analyzed. In both two scenarios, new types of radiative electroweak symmetry breaking are achieved with the effects of neutrino couplings. The Yukawa unification becomes compatible with the bottom quark mass and the experimental constraints from flavor-violating rare processes, and the hierarchical superparticle mass spectrum is obtained.

hep-ph↗