'Exotic vector-like pair' of color-triplet scalars

TL;DR

This paper introduces a minimal extension to the Standard Model involving exotic color-triplet scalars and a Majorana fermion, proposing mechanisms for neutron mass generation, baryogenesis, and potential experimental signatures.

Contribution

It presents a novel model with an exotic vector-like pair of scalars and a Majorana fermion, linking neutron mass, baryogenesis, and testable B-violating signatures.

Findings

Proposes a new B-violation mechanism via scalar mass terms.

Connects neutron mass generation with Post-Sphaleron Baryogenesis.

Suggests observable signatures in neutron-antineutron oscillations and collider experiments.

Abstract

We propose a minimal extension of Standard Model, generating a Majorana mass for neutron, connected with a mechanism of Post-Sphaleron Baryogenesis. We consider an `exotic vector-like pair' of color-triplet scalars, an extra Majorana fermion $\psi$, and a scalar field $\phi$, giving mass to $\psi$. The vector-like pair is defined `exotic' because of a peculiar mass term of the color-triplet scalars, violating Baryon number as $\Delta B=1$. A Post-Sphaleron Baryogenesis is realized through $\phi$-decays into six quarks (antiquarks), or through $\psi$-decays into three quarks (antiquarks). This model suggests some intriguing B-violating signatures, testable in the next future, in Neutron-Antineutron physics and LHC. We also discuss limits from FCNC. Sterile fermion can also be light as $1-100\, \rm GeV$. In this case, the sterile fermion could be (meta)-stable and $n-\bar{n}$ oscillation can be indirectly generated by two $n-\psi$, $\psi-\bar{n}$ oscillations, without needing of an effective Majorana mass for neutron. Majorana fermion $\psi$ can be a good candidate for WIMP-like dark matter.