arXiv subjects

M. Sugiura

Publications and source records attributed to M. Sugiura.

4 recordsLinked to original sources

arXiv1999

The effect of Majorana phase in degenerate neutrinos

There are physical Majorana phases in the lepton flavor mixing matrix when neutrinos are Majorana fermions. In the case of two degenerate neutrinos, the physical Majorana phase plays the crucial role for the stability of the maximal flavor mixing between the second and the third generations against quantum corrections. The physical Majorana phase of $π$ guarantees the maximal mixing to be stable against quantum corrections, while the Majorana phase of zero lets the maximal mixing be spoiled by quantum corrections when neutrino masses are of O(eV). The continuous change of the Majorana phase from $π$ to 0 makes the maximal mixing be spoiled by quantum corrections with O(eV) degenerate neutrino masses. On the other hand, when there is the large mass hierarchy between neutrinos, the maximal flavor mixing is not spoiled by quantum corrections independently of the Majorana phase.

hep-ph↗

arXiv1999

Energy-Scale Dependence of the Lepton-Flavor-Mixing Matrix

We study an energy-scale dependence of the lepton-flavor-mixing matrix in the minimal supersymmetric standard model with the effective dimension-five operators which give the masses of neutrinos. We analyze the renormalization group equations of kappa_{ij}s which are coefficients of these effective operators under the approximation to neglect the corrections of O(κ^2). As a consequence, we find that all phases in $κ$ do not depend on the energy-scale, and that only n_g-1 (n_g: generation number) real independent parameters in the lepton-flavor-mixing matrix depend on the energy-scale.

hep-ph↗

arXiv1998

The renormalization group analysis of the large lepton flavor mixing and the neutrino mass

The Superkamiokande experiment suggests the large flavor mixing between nu_mu and nu_tau. We show that the mixing angle receives significant corrections from the renormalization group equation (RGE) when both the second and the third generation neutrino masses are larger than O(0.1eV). This means that the mixing angle must be small at the decoupling scale of right-handed neutrinos in the model containing a sterile neutrino nu_s with the mass spectrum of m_nu_s = m_nu_e << m_nu_mu = m_nu_tau.

hep-ph↗

arXiv1996

Fermion Mass Generation in the D-dimensional Thirring Model as a Gauge Theory

Based on the Schwinger-Dyson (SD) equation, the fermion mass generation is further studied in the D(2<D<4)-dimensional Thirring model as a gauge theory previously proposed. By using a certain approximation to the kernel, we analytically obtained explicit form of the dynamical mass of fermion and the critical line in (N,1/g) space, where N is the number of fermions and g is the dimensionless vector-type four-fermion coupling constant. This analytical result is confirmed by the numerical solution for the SD equation with exact form of the kernel in (2+1) dimensions.

hep-th↗