Browsing by Author "Rodejohann, Werner"

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    The See-Saw Mechanism, Neutrino Yukawa Couplings, LFV Decays l_i to l_j + gamma and Leptogenesis
    (2005) Petcov, Serguey T.; Rodejohann, Werner; Shindou, Tetsuo; Takanishi, Yasutaka; Physics; Elementary Particle Theory
    The LFV charged lepton decays mu to e + gamma, tau to e + gamma and tau to mu + gamma and thermal leptogenesis are analysed in the MSSM with see-saw mechanism of neutrino mass generation and soft SUSY breaking with universal boundary conditions. The case of hierarchical heavy Majorana neutrino mass spectrum, M_1 << M_2 << M_3, is investigated.
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    U_{PMNS} = U_ell^dagger U_nu
    (2007-08-09T12:57:46Z) Hochmuth, K.A.; Petcov, Serguey T.; Rodejohann, Werner; Physics; Elementary Particle Theory
    We consider corrections to vanishing U_{e3} and maximal atmospheric neutrino mixing originating from the relation U = U_ell^dagger U_nu, where U is the PMNS mixing matrix and U_ell (U_nu) is associated with the diagonalization of the charged lepton (neutrino) mass matrix. We assume that in the limit of U_ell or U_nu being the unit matrix, one has U_{e3} = 0 and theta_{23} = pi/4, while the solar neutrino mixing angle is a free parameter. Well-known special cases of the indicated scenario are the bimaximal and tri-bimaximal mixing schemes. If U_{e3} \neq 0 and theta_{23} \neq pi/4 due to corrections from the charged leptons, |U_{e3}| can be sizable (close to the existing upper limit) and we find that the value of the solar neutrino mixing angle is linked to the magnitude of CP violation in neutrino oscillations. In the alternative case of the neutrino sector correcting U_{e3} = 0 and theta_{23} = pi/4, we obtain a generically smaller |U_{e3}| than in the first case. Now the magnitude of CP violation in neutrino oscillations is connected to the value of the atmospheric neutrino mixing angle theta_{23}. We find that both cases are in agreement with present observations. We also introduce parametrization independent "sum-rules" for the oscillation parameters.