Searching for a light $Z^{\prime }$ through Higgs production at the LHC

Abstract

We investigate the potential of LHC resonance searches in leptonic final states to probe the $Z^{\prime }$ in the minimal $U(1{)}_{B-L}$ model. Considering the current constraints on the $Z^{\prime }$ in terms of its mass $m_{Z^{\prime }}$ 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 $Z^{\prime }$ 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 $m_{Z^{\prime }}$ 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 $Z^{\prime }$ 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 $Z^{\prime }$. Finally, we also comment on the strength of $Z^{\prime }$ and Higgs mediated heavy neutrino processes by taking into account the constraints derived.

Comments: 26 pages, 9 figures, 9 references added, matches published version