Bottom-quark Forward-Backward Asymmetry, Dark Matter and the LHC

TL;DR

This paper proposes a new gauge boson to explain the bottom-quark forward-backward asymmetry anomaly, linking it to dark matter and LHC di-jet resonance observations, and discusses experimental constraints on this model.

Contribution

It introduces a novel $U(1)_D$ gauge boson model that accounts for the asymmetry anomaly and dark matter, consistent with collider and precision measurements.

Findings

The new gauge boson mass is constrained to around 115 GeV.

A di-jet resonance excess at similar mass supports the model.

The scenario remains compatible with existing experimental data.

Abstract

The LEP experiment at CERN provided accurate measurements of the $Z$ neutral gauge boson properties. Although all measurements agree well with the SM predictions, the forward backward asymmetry of the bottom-quark remains almost 3$\sigma$ away from the SM value. We proposed that this anomaly may be explained by the existence of a new $U(1)_D$ gauge boson, which couples with opposite charges to the right-handed components of the bottom and charm quarks. Cancellation of gauge anomalies demands the presence of a vector-like singlet charged lepton as well as a neutral Dirac (or Majorana) particle that provides a Dark Matter candidate. Constraints from precision measurements imply that the mass of the new gauge boson should be around $115$~GeV. We discuss the experimental constraints on this scenario, including the existence of a di-jet resonance excess at an invariant mass similar to the mass of this new gauge boson, observed in boosted topologies at the CMS experiment.