Phenomenological consequences of the seesaw mechanism in ${S}_{4}$ based models

Phenomenological consequences of the seesaw mechanism in $S_{4}$ based models

Federica Bazzocchi, Luca Merlo, and Stefano Morisi

Phys. Rev. D 80, 053003 – Published 1 September 2009

Abstract

Reference [1] proposed a flavor model based on the symmetry group $S_{4}$ , managing to describe fermion masses and mixings. The Weinberg operator has been used in order to provide the smallness of the neutrino masses, while a set of scalar fields, getting nonvanishing vacuum expectation values, spontaneously breaks down $S_{4}$ and provides the tri-bimaximal pattern as the lepton mixing matrix. Restricting to this setting, in this paper we analyze possible origins for the effective terms: the type I seesaw mechanism is the best known approach, but type II and III are also discussed. The phenomenology related to these models is various and future experiments could in principle discriminate among these proposals. Furthermore, we compare our realizations to two relevant $A_{4}$ based models, also predicting the tri-bimaximal lepton mixing, and we find that an analysis of the $0 ν 2 β$ -decay parameters could distinguish among all these realizations. The introduction of new physics beyond the standard model, like heavy right-handed neutrinos, scalar triplets, and fermion triplets, let us investigate leptogenesis, and this provides constraints in the realization of the models.

Received 4 March 2009

DOI:https://doi.org/10.1103/PhysRevD.80.053003

Authors & Affiliations

Federica Bazzocchi^1,*, Luca Merlo^2,†, and Stefano Morisi^3,‡

¹Department of Physics and Astronomy, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
²Dipartimento di Fisica ”G. Galilei,” Università di Padova INFN, Sezione di Padova, Via Marzolo 8, I-35131 Padua, Italy
³AHEP Group, Institut de Física Corpuscular C.S.I.C./Universitat de València Edicio Institutos de Paterna, Apt 22085, E-46071 Valencia, Spain

^*fbazzoc@few.vu.nl
^†merlo@pd.infn.it
^‡morisi@ic.uv.es

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Vol. 80, Iss. 5 — 1 September 2009

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Images

Figure 1
In both figures, $| m_{e e} |$ as a function of the lightest neutrino mass is plotted. The pinstriped bands represent the possible regions considering only the exact TB pattern, while the homogeneous ones are the predictions of the specific models: on the left the present proposal and on the right the analysis in 19. The band with the vertical lines refers to the NH, while the one with the horizontal lines to the IH. The darker homogeneous region corresponds to the NH, while the lighter one to the IH. The present bound from the Heidelberg-Moscow experiment [49] is shown in dark gray and the future sensitivity of CUORE ( $\sim 15 meV$ ), Majorana and GERDA III ( $\sim 20 meV$ ), and GERDA II ( $\sim 90 meV$ ) experiments are represented by the horizontal dashed lines, while the future sensitivity of 0.2 eV of KATRIN experiment [50] is shown by the vertical dashed line.Reuse & Permissions
Figure 2
In both figures, the sum of the neutrino masses as a function of the lightest mass. The darker region refers to the NH and the lighter one to the IH. On the left, the present proposal, and on the right, the analysis in 19. The vertical dashed line represents the future sensitivity of 0.2 eV from KATRIN experiment and the horizontal ones refer to the cosmological bounds (see the text for more details).Reuse & Permissions
Figure 3
In both figures, $| m_{e e} |$ as a function of the physical Majorana phase $α_{21}$ . The darker region refers to the NH and the lighter one to the IH. On the left, the present proposal, and on the right, the analysis in 19. The present bound from the Heidelberg-Moscow experiment is shown in dark gray and the future sensitivity of CUORE ( $\sim 15 meV$ ), Majorana and GERDA III ( $\sim 20 meV$ ), and GERDA II ( $\sim 90 meV$ ) experiments are dashed.Reuse & Permissions
Figure 4
In both figures, $| m_{e e} |$ as a function of the lightest neutrino mass is plotted. The pinstriped bands represent the possible regions considering only the exact TB pattern, while the homogeneous ones are the predictions of the AF model: on the left, the case with the seesaw scheme, and on the right, the effective case. The band with the vertical lines refers to the NH, while the one with the horizontal lines to the IH. The darker homogeneous region corresponds to the NH, while the lighter one to the IH: in the plot on the left the NH case contracts to a line. The experimental bounds are the same as in Fig. 1.Reuse & Permissions
Figure 5
On the left, $| m_{e e} |$ as a function of the lightest neutrino mass is plotted in the Niemeyer model. The pinstriped bands represent the possible regions considering only the exact TB pattern: the band with the vertical lines refers to the NH, while the one with the horizontal lines to the IH. The homogeneous region is the prediction of the model: only the NH and the QD can be accommodated. The experimental bounds are the same as in Fig. 1. On the right, $| m_{e e} |$ as a function of the Majorana phase is plotted. The experimental bounds are the same as in Fig. 3.Reuse & Permissions

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