Broken scaling neutrino mass matrix and leptogenesis based on A4 modular invariance

Abstract

In this work, we have proposed a modular A4 symmetric model of neutrino mass which, simultaneously, explains observed baryon asymmetry of the Universe (BAU). In minimal extension of the standard model (SM) with two right-handed neutrinos we work in a supersymmetric framework. At Type-I seesaw level, the model predicts scaling in the neutrino mass matrix. In order to have correct low energy phenomenology, we propose two possible scenarios of scale-breaking in the neutrino mass matrix emanating from Type-I seesaw. Scenario-1 is based on the dimension-5 Weinberg operator whereas scenario-2 implements Type-II seesaw via scalar triplet Higgs superfields (∆,$$ \overline{\Delta } $$ ∆ ¯ ). Interestingly, the breaking patterns in both, otherwise dynamically different scenarios, are similar which can be attributed to the same charge assignments of superfields (∆,$$ \overline{\Delta } $$ ∆ ¯ ) and the Higgs superfield Hu under modular A4 symmetry. The breaking is found to be proportional to the Yukawa coupling of modular weight 10 ($$ {Y}_{1,1\prime}^{10} $$ Y 1 , 1 ′ 10 ). We, further, investigates the predictions of the model under scenario-2 (Type-I+II) for neutrino mass, mixings and matter-antimatter asymmetry of the Universe. The model predicts normal hierarchical neutrino masses and provide a robust range (0.05 − 0.08)eV for sum of neutrino masses (Σmi). Lepton number violating 0νββ decay amplitude (Mee) is obtained to lie in the range (0.04 − 0.06)eV. Future 0νββ decay experiments such as NEXT and nEXO shall pose crucial test for the model. Both CP conserving and CP violating solutions are allowed in the model. Interesting correlations are obtained, specially, between Yukawa couplings of modular weight 2 and complex modulus τ. Contrary to $$ {Y}_2^2 $$ Y 2 2 and $$ {Y}_3^2 $$ Y 3 2 , the Yukawa coupling $$ {Y}_1^2 $$ Y 1 2 is found to be insensitive to τ and thus to CP violation because complex modulus τ is the only source of CP violation in the model. We, also, investigate the prediction of the model for BAU. The model exhibit consistent explanation of BAU for right-handed Majorana neutrino mass scale in the range ((1 − 5) × 1013) GeV.

Low scale leptogenesis in singlet-triplet scotogenic model

“…In order to have successful leptogenesis, in Type-I and Type-II seesaw extensions, the heavy singlet fermion and scalar triplet, respectively, contribute to the overall lepton asymmetry which further can be converted to baryon asymmetry via sphaleron processes [7][8][9][10][11][12][13][14][15]. The phenomena of leptogenesis in various extensions of the SM has been discussed thoroughly in the literature [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. The standard thermal leptogenesis based on Type-I seesaw model has a limitation of requiring very heavy Majorana fermions [36][37][38][39].…”

Fermi-LAT GeV excess and muon $g-2$ in a modular $A_4$ symmetry

“…1 In addition to the lepton sector, leptogenesis is discussed in refs. [48][49][50][51][52][53][54]. Semi-leptonic flavor changing neutral processes such as b → s ¯ , lepton flavor violations (LFVs), muon/electron g − 2, and EDM are mainly discussed in refs.…”

Subcritical regime of hybrid inflation with modular A4 symmetry

“…Moreover, in cosmology, models with dark matter candidates [79][80][81][82][83][84][85][86] have been considered and refs. [87][88][89][90][91][92][93][94][95] have applied it to leptogenesis.…”