arXiv subjects
Publications and source records attributed to Xiang-Jun Chen.
Neutrino flavor conversion is assumed to be induced by right-handed neutrino flavor conversion via seesaw mechanism. Neutrino oscillation is the macroscopic phenomenon before all neutrino flavor-flip interactions reaching equilibrium. The model for the hypothesis is the extension by introducing large mass Majorana right-handed neutrino into the Standard Model and exerting horizontal symmetry only on the right-handed neutrino sector.
Neutrino oscillation is phenomenon of random transition from a flavor state of neutrino to another, and should obey quantum statistics theory, and constitutes Markoffian process. The process is depicted by method of CTRW (continuous time random walk), and the time-evolution formula of flavor distribution of neutrino beam has been established. The simulation with Markoffian model for solar and cosmic ray neutrino indicates neutrino oscillation will arrive at equilibrium flavor distribution of three-fold maximum if propagation time is long enough, which is consistent to the data of SK and SNO experiments.
We propose an idea that the observed CP violation in neutrino oscillation is originated from the phase in right-handed neutrino mixing by seesaw mechanism. We add small breaking terms $M_{ij}N_{R_i}N_{R_j} $ in model based on $A_4$ symmetry to generate non-diagonal right-handed neutrino mixing, which will give a small correction to TBM mixing via seesaw mechanism with nonzero reactor angle and CP violating phase. We estimate the CP violating phase by investigating the process of leptogenesis due to the decay of right-handed neutrino.
$B_s^0\rightarrow D_s^{-}$ and $B_s^0\rightarrow D_s^{*-}$ weak transition form factors are estimated for the whole physical region with a method based on an instantaneous approximated Mandelstam formulation of transition matrix elements and the instantaneous Bethe-Salpeter equation. We apply the estimated form factors to branching ratios, CP asymmetries and polarization fractions of non-leptonic decays within the factorization approximation. And we study the non-factorizable effects and annihilation contributions with the perturbative QCD approach. The branching ratios of semi-leptonic $B_s^0\rightarrow D_s^{(*)-}l^+ν_l$ decays are also evaluated. We show that the calculated decay rates agree well with the available experimental data. The longitudinal polarization fraction of $B_s\rightarrow D_s^*V(A)$ decays are $\sim0.8$ when $V(A)$ denotes a light meson, and are $\sim0.5$ when $V(A)$ denotes a $D_q$ ($q=d,s$) meson.
An explicit two-soliton solution for the derivative nonlinear Schrödinger equation with nonvanishing boundary conditions is derived, demonstrating details of interactions between two bright solitons, two dark solitons, as well as one bright soliton and one dark soliton. Shifts of soliton positions due to collisions are analytically obtained, which are irrespective of the bright or dark characters of the participating solitons.
A symbolic computation technique is developed to calculate adiabatic evolution equations for parameters of the perturbed DNLS/MNLS solitons obtained by the recently developed direct perturbation theory [X.-J. Chen and J. Yang, Phys. Rev. E {\bf 65}, 066608(2002)]. Effects of the intrapulse Raman scattering, third-order group velocity dispersion, and narrow-banded filters with nonlinear gain on the MNLS solitons are studied as examples.