Model-Independent Constraints on Abelian Z ′ Couplings within the ATLAS Data on Dilepton Production Processes at √ s = 13 TeV

Abstract

Study of lepton pair production is a powerful test of the Standard Model (SM) and can be used to search for phenomena beyond the SM. New heavy neutral bosons Z ′ decaying to charged lepton pairs l +l − (l = e, µ) are predicted by many scenarios of new physics, including models with extended gauge sector. We estimate the LHC Z ′ discovery potential with Run 2 data comprised of 36.1 fb−1 of pp collisions at √ s = 13 TeV and recorded by ATLAS detector at the CERN LHC. The model-independent constraints on Z ′ fermion couplings were obtained for the first time for a selected set of Z ′ signal mass points of MZ′ = 2, 3, and 4 TeV by using the ATLAS data collected at the LHC. The analysis is based on the derived earlier special relations between the Z ′ couplings proper to the renormalizable theories. Taking into account the dependence of Z − Z ′ mixing angle θ0 on Z ′ axial-vector coupling a, the limits on θ0 are established as θ0 < 10−4 − 10−3 in the investigated Z ′ mass range.