Constraints on [formula omitted] from LHC data

Manuel Drees,Meng Shi,Zhongyi Zhang

doi:10.1016/j.physletb.2019.02.029

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.

Highlights

There are several reasons for considering the extension of the gauge group of the Standard Model (SM) by another Abelian U (1) factor
We recast a large number of LHC analyses, summarized in Table, from both the CMS and ATLAS collaborations in the CheckMATE framework in order to constrain the U (1)Lμ−Lτ extension of the SM
We focus on the new Z gauge boson predicted by this model, whose mass and coupling are the main free para√meters relevant for LHC physics

Summary

Introduction

There are several reasons for considering the extension of the gauge group of the Standard Model (SM) by another Abelian U (1) factor. Note that the U (1)Lμ−Lτ model can accommodate successful neutrino masses even with the simplest Higgs sector [ , ], and can be extended to contain a dark matter particle that is charged under the new symmetry but satis es the stringent direct search constraints [ , ]. In principle, this model could explain the difference between SM prediction and measurement of the anomalous magnetic moment of the muon (gμ − 2); bounds on νμN → νμμ+μ−N “trident” production [ ], where N stands for some nucleus, exclude this possibility for mZ > 0.5 GeV. This bound is always satis ed for gμτ ≤ 3 and qDM ≤ 2

Application to LHC Data

List of Analyses

Conclusions

Morad using

Findings

Albert boson