Right-handed neutrinos, domain walls and tadpoles in the superstring inspired $\mu\nu$SSM

TL;DR

This paper explores how superstring-inspired $mbda u$SSM models utilize right-handed neutrinos to address the $mbda$- and $nu$-problems, while avoiding domain wall and tadpole issues through non-renormalizable and non-perturbative effects.

Contribution

It introduces a superstring framework for the $mbda u$SSM that allows selective superpotential terms to solve key problems and discusses mechanisms for generating necessary neutrino mass terms.

Findings

Embedding in superstrings provides flexibility to avoid domain wall and tadpole problems.

Non-renormalizable and non-perturbative effects can generate necessary superpotential terms.

Right-handed neutrinos can acquire extra $U(1)$ charges, enabling stringy mechanisms for Majorana mass terms.

Abstract

We discuss the special role of right-handed neutrinos in the $\mu\nu$SSM for solving the $\mu$- and $\nu$-problems, simultaneously avoiding the potential domain wall and tadpole problems, In particular, embedding the $\mu\nu$SSM in the framework of superstrings implies that not all gauge invariant terms are necessarily present in the superpotential, and thus there is more flexibility to allow only those that avoid the domain wall and tadpole problems to be present. These can be non-renormalizable terms of dimension 4 or terms of higher dimensions. In addition, non-perturbative effects can also solve both problems. We discuss another implication of the superstring inspired $\mu\nu$SSM, since the right-handed neutrino is expected to have extra $U(1)$ charges at high energies. In this case, the cubic right-handed neutrino terms in the superpotential, helpful for generating Majorana masses and solving domain wall and tadpole problems, can arise through a variety of stringy mechanisms.