Muon reconstruction performance of the ATLAS detector in proton--proton collision data at $\sqrt{s}$=13 TeV

TL;DR

This paper evaluates the performance of muon identification and reconstruction in the ATLAS detector using 13 TeV proton-proton collision data, demonstrating high efficiency, good momentum resolution, and accurate simulation modeling.

Contribution

It provides detailed measurements of muon reconstruction efficiency, momentum scale, and resolution at 13 TeV, validated against Monte Carlo simulations, using early LHC data.

Findings

Reconstruction efficiency close to 99% across most phase space.

Momentum resolution of 1.7-2.3% in the central region.

Momentum scale known with 0.05% uncertainty.

Abstract

This article documents the performance of the ATLAS muon identification and reconstruction using the first LHC dataset recorded at $\sqrt{s}$ = 13 TeV in 2015. Using a large sample of $J/\psi\to\mu\mu$ and $Z\to\mu\mu$ decays from 3.2 fb$^{-1}$ of $pp$ collision data, measurements of the reconstruction efficiency, as well as of the momentum scale and resolution, are presented and compared to Monte Carlo simulations. The reconstruction efficiency is measured to be close to $99\%$ over most of the covered phase space ($|\eta|<2.5$ and $5 < p_{T} < 100$ GeV). The isolation efficiency varies between $93\%$ and $100\%$ depending on the selection applied and on the momentum of the muon. Both efficiencies are well reproduced in simulation. In the central region of the detector, the momentum resolution is measured to be $1.7\%$ ($2.3\%$) for muons from $J/\psi\to\mu\mu$ ($Z\to\mu\mu$) decays, and the momentum scale is known with an uncertainty of $0.05\%$. In the region $|\eta |>2.2$, the $p_{T} $ resolution for muons from $Z\to\mu\mu$ decays is $2.9\%$ while the precision of the momentum scale for low-$p_{T} $ muons from $J/\psi\to\mu\mu$ decays is about $0.2\%$.