Speaker
Description
The finite modular groups are isomorphic to permutation groups e.g. $\Gamma_{3}\simeq$ A$_4$. Apart from usual irreducible representations of the permutation groups, they have modular weights as new symmetry charges. The Yukawa couplings transforms as modular forms of complex modulus $\tau$ acquiring suitable charges of the underlying symmetry. In this work, we propose a scenario implementing the correction to scaling neutrino mass matrix and investigate baryogenesis based on A$_4$ modular symmetry within Type-I+II seesaw framework. In fact the scaling neutrino mass matrix results in vanishing reactor mixing angle ($\theta_{13}$), inverted ordering of neutrino masses with vanishing lowest neutrino mass eigenvalue ($m_{3}=0$). In the proposed model, field content comprises of the standard model particles, two chiral neutrino superfields ($N_{1}^{c}$, $N_{2}^{c}$) and scalar singlet weighton field ($\phi$) which results in scaling neutrino mass matrix through Type-I seesaw. The correction to scaling neutrino mass matrix is manifested through Type-II seesaw obtained by introducing a supersymmetric pair of scalar triplet fields ($\Delta$,$\bar{\Delta}$). In particular, correction to scaling neutrino mass matrix is found to be proportional to modular Yukawa couplings of weight 10 ($Y_{1,1'}^{10}$). The model satisfies the neutrino oscillation data and cosmological constraint on sum of neutrino masses ($\sum m_{i}\leq 0.12$eV). The modular Yukawa couplings of modular weight 2 are sensitive to the imaginary part of complex modulus $\tau$, only. Also, we have studied the implications of the model for neutrinoless double beta decay ($0\nu\beta\beta$). The effective Majorana mass parameter ($M_{ee}$) is found to be in range ($0.04-0.06$) eV which is well within the sensitivity reach of $0\nu\beta\beta$ decay experiments. Furthermore, there exist robust lower bound on sum of neutrino masses ($\sum m_{i}\geq 0.05$ eV). Also, in order to generate a consistent baryon asymmetry of the universe the right-handed neutrino mass is found to be in the range $((1-5)\times10^{13})$ GeV implying that the flavor effects are negligible.
| Session | Neutrino Physics |
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