Constraints on U(1)Lμ−Lτ from LHC data

Abstract

In this study, we apply LHC data to constrain the extension of the Standard Model by an anomaly–free U(1)Lμ−Lτ gauge group; this model contains a new gauge boson (Z′) and a scalar dark matter particle (ϕDM). We recast a large number of LHC analyses of multi–lepton final states by the ATLAS and CMS collaborations. We find that for 10GeV<mZ′<60 GeV the strongest constraint comes from a dedicated Z′ search in the 4μ final state by the CMS collaboration; for larger Z′ masses, searches for final states with three leptons plus missing ET are more sensitive. Searches for final states with two leptons and missing ET, which are sensitive to Z′ decays into dark matter particles, can only probe regions of parameter space that are excluded by searches in the 3 and 4 lepton channels. The combination of LHC data excludes values of Z′ mass and coupling constant that can explain the deficit in gμ−2 for 4GeV≤mZ′≤500 GeV. However, for much of this range the LHC bound is weaker than the bound that can be derived from searches for “trident” events in neutrino–nucleus scattering. Keywords: Dark matter, Beyond Standard Model, LHC, Multi-lepton