Marginal operators and supersymmetry enhancement in 3d S-fold SCFTs

The study of exactly marginal deformations of superconformal field theories is a topic that has received considerable attention due to their rich properties. We investigate the $$ \mathcal{N} $$ N = 2 preserving exactly marginal operators of 3d S-fold SCFTs. Two families of such theories are considered: one is constructed by gauging the diagonal flavour symmetry of the T(U(2)) and T(U(3)) theories, and the other by gauging the diagonal flavour symmetry of the $$ {T}_{\left[2,{1}^2\right]}^{\left[2,{1}^2\right]}\left( SU(4)\right) $$ T 2 1 2 2 1 2 SU 4 theory. In both families, it is possible to turn on a Chern-Simons level for each gauge group and to couple to each theory various numbers of hypermultiplets. The detailed analysis of the exactly marginal operators, along with the superconformal indices, allows us to determine whether supersymmetry gets enhanced in the infrared and to deduce the amount of supersymmetry of the corresponding SCFT.

Realization of the minimal extended seesaw mechanism and the TM2 type neutrino mixing

We construct a neutrino mass model based on the flavour symmetry group A4×C4×C6×C2 which accommodates a light sterile neutrino in the minimal extended seesaw (MES) scheme. Besides the flavour symmetry, we introduce a U(1) gauge symmetry in the sterile sector and also impose CP symmetry. The vacuum alignments of the scalar fields in the model spontaneously break these symmetries and lead to the construction of the fermion mass matrices. With the help of the MES formulas, we extract the light neutrino masses and the mixing observables. In the active neutrino sector, we obtain the TM2 mixing pattern with non-zero reactor angle and broken μ-τ reflection symmetry. We express all the active and the sterile oscillation observables in terms of only four real model parameters. Using this highly constrained scenario we predict $$ {\sin}^2{\theta}_{23}={0.545}_{-0.004}^{+0.003},\sin \delta =-{0.911}_{-0.005}^{+0.006},{\left|{U}_{e4}\right|}^2={0.029}_{-0.008}^{+0.009},{\left|{U}_{\mu 4}\right|}^2={0.010}_{-0.003}^{+0.003}\kern0.5em \mathrm{and}\kern0.5em {\left|{U}_{\tau 4}\right|}^2={0.006}_{-0.002}^{+0.002} $$ sin 2 θ 23 = 0.545 − 0.004 + 0.003 , sin δ = − 0.911 − 0.005 + 0.006 , U e 4 2 = 0.029 − 0.008 + 0.009 , U μ 4 2 = 0.010 − 0.003 + 0.003 and U τ 4 2 = 0.006 − 0.002 + 0.002 which are consistent with the current data.