LHC and HL-LHC bounds on visible and invisible Z′ decays in the B−L model

Abstract

In this work, we use published results by the ATLAS Collaboration collected at LHC Run 2 at a center-of-mass energy of s=13TeV with an integrated luminosity of 139 fb−1 to derive lower-mass limits on the Z′ gauge boson associated with the B−L gauge symmetry. Using dilepton data, we find that MZ′>4 TeV (6 TeV) for gB−L=0.1 (gB−L=0.5) in the absence of invisible decays. Once invisible decays are turned on, these limits are substantially relaxed. Assuming an invisible branching ratio of BRinv=0.9, the LHC bound is loosened up to MZ′>4.8 TeV for gB−L=0.5. This analysis confirms that the LHC is able to impose stricter constraints than the bounds established by experiments at LEP. We also estimate the projected High-Luminosity LHC bounds at s=14 TeV and a planned integrated luminosity of L=3 ab−1 that will probe Z′ masses up to 7.5 TeV. Published by the American Physical Society 2025