Next-to-minimal $R$-symmetric model: Dirac gaugino, Higgs mass and invisible width

TL;DR

This paper explores a singlet extension of an $U(1)_R$ symmetric model with Dirac gauginos, demonstrating compatibility with the observed Higgs mass and constraints from invisible decays, while introducing light scalar and fermion states.

Contribution

It introduces a novel singlet extension of the $U(1)_R$ symmetric model that achieves a 125 GeV Higgs mass with low SUSY scale and suppressed D-term potential, including light pseudo-moduli and pseudo-Goldstino.

Findings

The Higgs mass remains consistent with perturbative unification at low SUSY scales.

Light scalar and fermion states can exist without conflicting with invisible decay constraints.

The presence of light degrees of freedom can slightly reduce the Higgs mass by a few percent.

Abstract

We study a singlet extension of the minimal $U(1)_R$ symmetric model, which shares nice properties of Dirac gauginos and $R$-symmetric Higgs sector. At the same time, a superpotential coupling of $R$-charged singlet to the Higgs doublets can give a substantial contribution to the Higgs boson mass. We show that the 125 GeV Higgs boson is consistent with perturbative unification, even if the SUSY scale is as low as 1 TeV and if the $D$-term Higgs potential is suppressed as is often the case in Dirac gauginos. The model also contains a light scalar and fermion, pseudo-moduli and pseudo-Goldstino: The former gets a mass mainly from SUSY breaking soft terms, in addition to a small explicit $R$-symmetry breaking for the latter. We examine how the Higgs mass and width are affected by these light degrees of freedom. Specifically we find thatdepending on parameters of $R$-charged Higgses, the pseudo-moduli lighter than a half of the SM-Higgs boson mass is still allowed by the constraints from invisible decays of the $Z$ and Higgs bosons. We also find that such a light scalar can reduce the Higgs boson mass, at most by a few percents.