Signals for a 2HDM with $Z'$ at the LHC

TL;DR

This paper explores a neutrinophilic $U(1)$ extension of the Standard Model featuring a new $Z'$ gauge boson, focusing on its production via scalar decays at the LHC and analyzing potential multilepton signals for discovery.

Contribution

It introduces a novel neutrinophilic $U(1)$ model with detailed scalar sector analysis and investigates LHC signals from scalar decays involving a weakly coupled $Z'$ boson.

Findings

Scalar decays can produce detectable multilepton signals at the LHC.

The $Z'$ can be produced indirectly through scalar decay channels.

Potential for discovering 2HDM scalars via multilepton signatures.

Abstract

We consider a neutrinophilic $U(1)$ extension of the Standard Model (SM) under which only a second Higgs doublet and SM singlet scalars and fermions are charged. The new gauge boson $Z'$ couples to SM minimally, generated by $Z-Z'$ mixing. As the $Z'$ is very weakly coupled, it can mostly be produced through the decay of the scalars from the second Higgs doublet at the Large Hadron Collider (LHC). We discuss the scalar sector of the model in detail and consider decay modes such as $(H^{\pm} \to W^\pm Z', h_2 \to VV, (V = W^\pm, Z, Z'), A_2 \to h_1 Z'(Z))$ that lead to multilepton signals at the LHC from the pair production of the scalars. We analyze the signal with a representative value of the $Z'$ mass to show the discovery potential of the 2HDM scalars at the LHC.