Testing lepton flavor models at ESSnuSB

Abstract

We review and investigate lepton flavor models, stemming from discrete non-Abelian flavor symmetries, described by one or two free model parameters. First, we confront eleven one-and seven two-parameter models with current results on leptonic mixing angles from global fits to neutrino oscillation data. We find that five of the one-and five of the two-parameter models survive the confrontation test at 3σ. Second, we investigate how these ten one-and two-parameter lepton flavor models may be discriminated at the proposed ESSnuSB experiment in Sweden. We show that the three one-parameter models that predict sin δ CP = 0 can be distinguished from those two that predict | sin δ CP | = 1 by at least 7σ. Finally, we find that three of the five one-parameter models can be excluded by at least 5σ and two of the one-parameter as well as at most two of the five two-parameter models can be excluded by at least 3σ with ESSnuSB if the true values of the leptonic mixing parameters remain close to the present best-fit values.

Discrete Flavor Symmetries and Lepton Masses and Mixings

“…Such studies crucially depend on the breaking pattern of G f into its residual subgroups for charged lepton sector G e and neutrino sector G ν . For example, in [284], the authors have studied implication of breaking of G f × CP (with G f = A 4 , S 4 , A 5 ) into G e > Z 2 , G ν = Z 2 × CP in the context of ESSnuSB experiment [285]. Such breaking pattern is usually observed in the semi-direct approach of flavor model building [286].…”

Testing neutrino flavor models

“…The presence of mixing sum rules significantly increases the testability of flavor models and can guide the requirements on the target precision for the measurements of the mixing parameters. Indeed, with the help of mixing sum rules one can forecast the impact of measurements at future neutrino oscillation experiments [28][29][30][31][32][33][34][35] like DUNE, T2HK, ESSνSB, and JUNO.…”

“…The corresponding mixing patterns are characterized by one free angle parameter. See [35] for a summary of such scenarios and original references.…”

“…2. Best-fit predictions of the models based on discrete symmetries broken to certain residual symmetries of the lepton mass matrices [28,35], and the models based on modular symmetries discussed in [47,73,74]. The gray regions are the current 3σ ranges for NO from [1] (the ranges for IO are very similar).…”

Leptonic sum rules from flavour models with modular symmetries

“…Neutrino mass sum rules can be tested in experiments measuring the absolute neutrino mass scale or experiments that provide information on the sum of the neutrino masses. A number of studies have shown, in particular, that checking the validity of the leptonic mixing sum rules using the currently available and prospective data on the neutrino mixing angles and the Dirac CPV phase is an extremely powerful method of discriminating between different discrete symmetry models and, more generally, of testing the non-Abelian discrete symmetry approach to the neutrino mixing problem (see, e.g., [32][33][34][35]).…”