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Neutrino mass determination from a four-zero texture mass matrix

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 Added by Juan Barranco
 Publication date 2012
  fields
and research's language is English




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We analyze the different parametrizations of a general four-zero texture mass matrices for quarks and leptons, that are able to reproduce the CKM and PMNS mixing matrices. This study is done through a Chi-Square analysis. In quark sector, only four solutions are found to be compatible with CKM mixing matrix. In leptonic sector, using the last experimental results about the mixing angles in the neutrino sector, our Chi-Square analysis shows a preferred value for m_nu_3 to be around 0.05 eV independently of the parametrization of the four-zero texture mass matrices chosen for the charged leptons and neutrinos.



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The model of neutrino mass matrix with minimal texture is now tightly constrained by experiment so that it can yield a prediction for the phase of CP violation. This phase is predicted to lie in the range $delta_{CP}=0.77pi - 1.24pi$. If neutrino oscillation experiment would find the CP violation phase outside this range, this means that the minimal-texture neutrino mass matrix, the element of which is all real, fails and the neutrino mass matrix must be complex, i.e., the phase must be present that is responsible for leptogenesis.
We studied the phenomenological implications of texture zeros in the neutrino mass matrix of the minimal left-right symmetric model (LRSM). Since the possibility of maximum zeros reduces the maximum number of free parameters of the model making it more predictive, we considered only those cases with maximum possible texture zeros in light neutrino mass matrix $M_{ u}$, Dirac neutrino mass matrix $M_D$ and heavy right-handed (RH) neutrino mass matrix $M_{RR}$. We then computed the correlations among the different light neutrino parameters and then the new physics contributions to neutrinoless double beta decay (NDBD) for the different texture zero cases. We find that for RH neutrino masses above 1 GeV, the new physics contributions to NDBD can saturate the corresponding experimental bound.
We investigate the possibility of expressing the charged leptons and neutrino mass matrices as linear combinations of generators of a single finite group. Constraints imposed on the resulting mixing matrix by current data restrict the group types, but allow a non zero value for the theta_13 mixing angle
Using the residual symmetry approach, we propose a complex extension of the scaling ansatz on $M_ u$ which allows a nonzero mass for each of the three light neutrinos as well as a nonvanishing $theta_{13}$. Leptonic Dirac CP violation must be maximal while atmospheric neutrino mixing need not to be exactly maximal. Each of the two Majorana phases, to be probed by the search for $0 u betabeta$ decay, has to be zero or $pi$ and a normal neutrino mass hierarchy is allowed.
In view of the latest T2K and MINOS neutrino oscillation data which hint at a relatively large theta_13, we perform a systematic study of the Majorana neutrino mass matrix M_nu with two independent texture zeros. We show that three neutrino masses (m_1, m_2, m_3) and three CP-violating phases (delta, rho, sigma) can fully be determined from two neutrino mass-squared differences (delta m^2, Delta m^2) and three flavor mixing angles (theta_12, theta_23, theta_13). We find that seven patterns of M_nu (i.e., A_{1,2}, B_{1,2,3,4} and C) are compatible with current experimental data at the 3-sigma level, but the parameter space of each pattern is more strictly constrained than before. We demonstrate that the texture zeros of M_nu are stable against the one-loop quantum corrections, and there exists a permutation symmetry between Patterns A_1 and A_2, B_1 and B_2 or B_3 and B_4. Phenomenological implications of M_nu on the neutrinoless double-beta decay and leptonic CP violation are discussed, and a realization of those texture zeros by means of the Z_n flavor symmetries is illustrated.
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