Searching for a light $Z'$ through Higgs production at the LHC

TL;DR

This paper explores how the LHC can detect a light $Z'$ boson in the $U(1)_{B-L}$ model through leptonic final states, especially four-lepton signals, including long-lived scenarios, using current and future collider data.

Contribution

It analyzes the sensitivity of dilepton and four-lepton final states at the LHC to light $Z'$ bosons, including long-lived cases, within the minimal $U(1)_{B-L}$ model, considering current constraints.

Findings

Four-lepton final state sensitive to $Z'$ masses as low as 0.25 GeV.

Strong sensitivity for $Z'$ detection with Higgs mixing $ ext{sin}\alpha=0.3$.

Potential to probe displaced vertices from long-lived $Z'$ at the HL-LHC.

Abstract

We investigate the potential of LHC resonance searches in leptonic final states to probe the $Z'$ in the minimal $U(1)_{B-L}$ model. Considering the current constraints on the $Z'$ in terms of its mass $m_{Z'}$ and the associated gauge coupling $g_{B-L}$ as well as constraints in the Higgs sector, we analyse the potential of dilepton and four lepton final states for $Z'$ production. This includes Drell-Yan production, Higgs mediated decays and final state radiation processes concentrating only on the ATLAS and CMS detectors at the LHC. We show that the four-lepton final state is sensitive to $m_{Z'}$ as low as 0.25 GeV. Furthermore, setting the Higgs mixing to $\sin\alpha = 0.3$, this final state has a strong sensitivity and it probes regions of parameter space where the $Z'$ is long-lived. We demonstrate the sensitivity at the High Luminosity LHC and comment on the potential of probing displaced vertices due to long-lived $Z'$. Finally, we also comment on the strength of $Z'$ and Higgs mediated heavy neutrino processes by taking into account the constraints derived.