tailieunhanh - On the CP violation phase in a neutrino mixing model with an A4 flavor symmetry

Neutrino masses and mixing in an extended standard model acquiring an A4 flavor symmetry are considered. The corresponding three-neutrino mixing matrix obtained via a perturbative method allows us to determine the Dirac CP violation phase (δCP) as a function of the mixing angles (θ12,θ23,θ13). Then, numerical values and distributions of δCP are given. The latter values are quite close to the global fits of the experimental data for both the normal ordering and inverse ordering of the neutrino masses. | Communications in Physics, Vol. 26, No. 1 (2016), pp. 1-9 DOI: ON THE CP VIOLATION PHASE IN A NEUTRINO MIXING MODEL WITH AN A4 FLAVOR SYMMETRY PHI QUANG VAN AND NGUYEN THI HONG VAN† Institute of Physics, Vietnam Academy of Science and Technology † E-mail: nhvan@ Received 09 March 2016 Accepted for publication 14 April 2016 Abstract. Neutrino masses and mixing in an extended standard model acquiring an A4 flavor symmetry are considered. The corresponding three-neutrino mixing matrix obtained via a perturbative method allows us to determine the Dirac CP violation phase (δCP ) as a function of the mixing angles (θ12 , θ23 , θ13 ). Then, numerical values and distributions of δCP are given. The latter values are quite close to the global fits of the experimental data for both the normal ordering and inverse ordering of the neutrino masses. Keywords: neutrino mass and mixing, flavor symmetries, models beyond the standard model. Classification numbers: , , . I. INTRODUCTION Standard model (SM) [1–4] has been confirmed as an excellent model of elementary particles and their interactions, especially after the discovery of the Brout-Englert-Higgs boson (Higg boson) by ATLAS and CMS [5, 6], which are the two biggest LHC collaborations (see [7] for a review on the discovering of the Higgs boson). The SM, however, cannot explain a number of phenomena including that of the neutrino masses and mixing [8, 9]. They, therefore, call for an extension of the SM. One of the extensions of the SM which has attracted great interest for last ten years is that with a flavor symmetry. A widely investigated flavor symmetry is based on the discrete group A4 (see, for example, [10,11]). This symmetry can make a neutrino mixing scheme tribi-maximal (TBM). The recent experimental data [12,13], however, shows that the mixing angle θ13 and the Dirac CP-violation phase (CPV) δCP are non-zero. That means that the TBM scheme is no .