Neutrino mass and mixing

At present, it is well known that neutrinos are massive that contradicts the Standard Model (SM). The experimental data show that masses of neutrinos are tiny small and neutrinos mix with special pattern in approximately tribimaximal form. The neutrino masses, dark matter and the baryon asymmetry of Universe (BAU) are the facts requiring extension of the SM.

12p vijichoo2711 04-06-2021 9 1   Download

The thesis is devoted to constructing and evaluating versions of the SM extended with an A4 symmetry to explain some of the problems of neutrino physics. Within these extended models, the results on neutrino masses and mixing, derived by the perturbation method, are very closed to the global fit. In two models, a relation between the Dirac CPV phase and the mixing angles is established. In particular, the models predict Dirac CPV phase δCP and effective mass of neutrinoless double beta decay jhmeeij in good agreement with the current experimental data.

26p capheviahe27 23-02-2021 17 3   Download

Possible contributions to neutrinoless double beta (ββ)0ν decay in the economical 3-3-1 model are discussed. We show that the (ββ)0ν decay in this model is due to both sources— Majorana hMν iL and Dirac hMν iD neutrino masses. If the mixing angle between charged gauge bosons, the standard model W and bilepton Y is in range of the ratio of neutrino masses hMν iL/hMν iD, then both the Majorana and Dirac masses simultaneously give contributions dominant to the decay. As results, constraints on the bilepton mass are also given.

11p nguyenxuankha_bevandan 14-08-2020 14 1   Download

We show that the mass matrix of electrically neutral gauge bosons in the recent proposed model based on SU(3)C ⊗ SU(3)L ⊗ U(1)X group with three neutrino singlets [9] has two exact eigenvalues and corresponding eigenvectors. Hence the neutral non-Hermitian gauge boson X0 µ is properly determined. With extra vacuum expectation values of the Higgs fields, there are mixings among charged gauge bosons W± and Y ± as well as among neutral gauge bosons Z,Z 0 and X0 .

11p thuyliebe 09-10-2018 41 1   Download

We show that the neutrino mass matrix of the Zee-Babu model is able to fit the recent data on neutrino masses and mixing with non-zero θ13 in the inverted neutrino mass hierarchy. The results show that the Majorana phases are equal to zero and the Dirac phase (δ) is predicted to either 0 or π, i. e, there is no CP violation in the Zee-Babu model at the two loop level. The effective mass governing neutrinoless double beta decay and the sum of neutrino masses are consistent with the recent analysis

8p thuyliebe 09-10-2018 27 0   Download

We study the seesaw realization of a A4 model with two Higgs singlets. In this model, the mixing angle θ13 and leptogenesis are zero if the components of right handed neutrino mass matrix resulting from the two Higgs singlets are exact degenerate. We then study the minimal breaking of the model by a tiny shift between aforementioned components. This minimal breaking results in deviations of lepton mixing angles from their tri-bimaximal mixing values in which the current experimental value of θ13 can be achieved.

11p thuyliebe 09-10-2018 20 1   Download

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.

10p thuyliebe 08-10-2018 33 1   Download