Noriyuki Oshimo

T-odd asymmetry mediated by neutralino in e+e- annihilation

Abstract T violation in the neutralino production and decay process e + +e − → x 1 + x j → x 1 + x 1 l + l − , is discussed in the supersymmetric standard model. The asymmetry of the angular distribution of the final leptons is calculated as a T violation effect. This asymmetry could be of order 10 −3 for the unpolarized electron beam and 10 −2 for the polarized beam, which may be observed in future experiments at LEP.

CP asymmetry for radiative B meson decay in the supersymmetric Standard Model

We study a rate asymmetry in the inclusive decay B → Xsγ, assuming the supersymmetric standard model based on N = 1 supergravity. A complex coefficient A for scalar-trilinear couplings is the source of CP violation, which is contained in the mass-squared matrices for squarks. The model parameters are non-trivially constrained by experimental results for the branching ratio of the radiative decay and for the electric dipole moments of the neutron and the electron. The decay rate asymmetry is predicted to be much larger than that by the standard model in a wide region of the parameter space compatible with the experiments. Its magnitude can be maximally around 0.1, which will be well accessible at B factories.

Antisymmetric Higgs representation in SO(10) for neutrinos

A Model based on SO(10) grand unified theory (GUT) and supersymmetry is presented to describe observed phenomena for neutrinos. The large mixing angles among different generations, together with the small masses, are attributed to the Higgs boson structure at the GUT energy scale. Quantitative discussions for these observables are given, taking into account their energy evolution.

Model for neutrino mixing based on SO(10)

Abstract Assuming grand unified theory (GUT) and supersymmetry, we propose a simple model which can consistently accommodate the masses and mixings for quarks and leptons. The grand unified group is SO(10), and 10, 120, and 126 representations are introduced for the Higgs superfields which give masses to the quarks and leptons. The differences of masses and mixings between the quarks and the leptons are attributed to the Higgs boson structure. Below the GUT energy scale, the model is the same as the minimal supersymmetric standard model except its inclusion of dimension-5 operators for the small neutrino masses. The renormalization group equations of the independent parameters for the Higgs couplings with the quarks and leptons are given explicitly to connect the two energy scales of GUT and electroweak theory.

Implications of Baryon Asymmetry for the Electric Dipole Moment of the Neutron

The supersymmetric standard model (SSM) contains a new source of CP violation in the mass-squared matrices for squarks, which could imply the t squark mediation of the charge transport mechanism producing the baryon asymmetry of the universe. This CP-violating source also induces the electric dipole moment (EDM) of the neutron. We show that this t-squark transport can lead to a baryon asymmetry consistent with its observed value within reasonable ranges of SSM parameters, where the neutron EDM has a magnitude slightly smaller than its experimental upper bound.

Neutron electric dipole moment from supersymmetric anomalous W -boson coupling

In the supersymmetric standard model (SSM) the W boson could have a nonvanishing electric dipole moment (EDM) through a one-loop diagram mediated by the charginos and neutralinos. Then the W-boson EDM induces the EDMs of the neutron and the electron. We discuss these EDMs, taking into consideration the constraints from the neutron and electron EDMs at the one-loop level induced by the charginos and squarks or sleptons. It is shown that the neutron and the electron could, respectively, have EDMs of the order of 10{sup {minus}26}ecm and 10{sup {minus}27}ecm, solely owing to the W-boson EDM. Since these EDMs do not depend on the values of the SSM parameters for the squark or slepton sector, they provide less ambiguous predictions for CP violation in the SSM. {copyright} {ital 1997} {ital The American Physical Society}

Decay rate asymmetry in B ---> X(s) gamma as a signature of supersymmetry

In the supersymmetric standard model, the radiative B-meson decay

Supersymmetric Contributions to

\stackrel{\ensuremath{\rightarrow}}{B}{X}_{s}\ensuremath{\gamma}

\BB

could receive a large contribution from a new source of flavor-changing neutral current, which also violates

and

\mathrm{CP}