Search for Dilepton Resonances with the ATLAS Detector and Run 2 Data

TL;DR

This paper reports a search for new heavy dilepton resonances in proton-proton collision data from the ATLAS detector at the LHC, setting limits on possible new particles up to 4.5 TeV in mass.

Contribution

First comprehensive search for dilepton resonances in Run 2 ATLAS data, establishing new mass exclusion limits for various theoretical models.

Findings

No significant excess observed over background.

Excluded resonance masses up to 4.5 TeV for certain models.

Set 95% CL upper limits on cross-section times branching ratio.

Abstract

A search for resonances in the dielectron and dimuon mass spectra from 250 GeV to 6 TeV is presented. The data were recorded during Run 2 of the LHC by the ATLAS experiment using proton-proton ($pp$) collisions with a center-of-mass energy of $\sqrt{s} = 13$ TeV. The integrated luminosity of the data corresponds to 139 fb$^{-1}$. The background models are a functional form fit to the data, and generic signal shapes are used to represent various models with different resonant widths and masses. No significant deviation from the expected background is observed and 95\% confidence level upper limits are set on the fiducial cross-section times branching ratio for models of various widths. For benchmark models, limits are converted to lower limits on the resonance mass and reach 4.5 TeV for the E$_6$ motivated $Z'_\psi$ boson.