arXiv subjects
Publications and source records attributed to Takuya Morozumi.
The light neutrino mass spectrum and mixing matrix of seesaw model including three right-handed neutrinos are studied for the most general case. An approximate formulae for mass eigenvalues, mixing matrix, and CP violation of neutrino oscillations are given.
We present a new mechanism for baryogenesis by introducing a heavy vector-like SU(2)_W singlet quark(s) with Q_{em}=2/3 quark U or Q_{em}=-1/3 quark D. The lifetime of the heavy quark is assumed to be in the range 2 \times 10^{-11}s < t < 1s. Being SU(2)_W singlet, it survives the electroweak phase transition era. It mixes with SU(2)_W doublet quarks with tiny mixing angles to satisfy the FCNC constraints, where a simple Z_2 symmetry is suggested for realizing this scheme. The heavy quark asymmetry is generated in analogy with the old GUT scenario.
We discuss the possibility of relating the size and sign of the observed baryon asymmetry of the universe to CP violation observable at low energies, in a framework where the observed baryon asymmetry is produced by leptogenesis through the out of the equilibrium decay of heavy Majorana neutrinos. We identify the CP violating phases entering in leptogenesis as well as those relevant for CP violation at low energies in the minimal seesaw model. We show that although in general there is no relation between these two sets of phases, there are specific frameworks in which such a connection may be established and we give a specific grand unification inspired example where such a connection does exist. We construct weak-basis invariants related to CP violation responsible for leptogenesis, as well as those relevant for CP violation at low energies.
We derive an effective Lagrangian for meson fields. This is done in the light-cone gauge for two-dimensional large-N_c QCD by using the bilocal auxiliary field method. The auxiliary fields are bilocal on light-cone space and their Fourier transformation determines the parton momentum distribution. As the first test of our method, the 't Hooft equation is derived from the effective Lagrangian.
We present the angular distribution of the rare B decay, $B \to K^* (\to K π) \ell^+ \ell^-$. By studying the azimuthal angle distribution in the low invariant mass region of dileptons, we can probe new physics effects efficiently. In particular, this distribution is found to be quite sensitive to the ratio of the contributions from two independent magnetic moment operators, which also contribute to $B \to K^* γ$. Therefore, our method can be very useful when new physics is introduced without changing the total decay rate of the $b \to s γ$. The angular distributions are compared with the predictions of the standard model, and are shown for the cases when the afore-mentioned ratio is different from the standard model prediction.