Atomki anomaly in gauged $U(1)_R$ symmetric model

TL;DR

This paper proposes a gauged $U(1)_R$ symmetric model to explain the Atomki anomaly, identifying a new gauge boson with the observed 17 MeV excess, and explores parameter regions consistent with experimental constraints.

Contribution

It introduces a $U(1)_R$ gauge symmetry model with specific Higgs fields to account for the Atomki anomaly and addresses neutrino-electron scattering constraints.

Findings

Identifies parameter space fitting the Atomki anomaly

Determines $U(1)_R$ charges to evade neutrino-electron scattering constraints

Shows compatibility with experimental bounds

Abstract

The Atomki collaboration has reported that unexpected excesses have been observed in the rare decays of Beryllium nucleus. It is claimed that such excesses can suggest the existence of a new boson, called $X$, with the mass of about $17$ MeV. To solve the Atomki anomaly, we consider a model with gauged $U(1)_R$ symmetry and identify the new gauge boson with the $X$ boson. We also introduce two $SU(2)$ doublet Higgs bosons and one singlet Higgs boson, and discuss a very stringent constraint from neutrino-electron scattering. It is found that the $U(1)_R$ charges of the doublet scalars are determined to evade the constraint. In the end, we find the parameter region in which the Atomki signal and all experimental constraints can be simultaneously satisfied.