Measurement of the nuclear modification factor for high-$p_{\mathrm{T}}$ charged hadrons in $p$+Pb collisions with the ATLAS detector

TL;DR

This paper measures the nuclear modification factor for high-$p_{\mathrm{T}}$ charged hadrons in $p$+Pb collisions at 5.02 TeV using ATLAS data, finding no significant deviation from unity at high transverse momentum.

Contribution

First measurement of the nuclear modification factor for high-$p_{\mathrm{T}}$ charged hadrons in $p$+Pb collisions at 5.02 TeV with detailed comparison to $pp$ spectra.

Findings

$R_{p\mathrm{Pb}}$ is consistent with unity at high $p_{\mathrm{T}}$

No significant nuclear modification observed in high-$p_{\mathrm{T}}$ region

Results provide baseline for understanding nuclear effects in proton-lead collisions.

Abstract

The charged hadron spectra in $p$+Pb and $pp$ collisions at $\sqrt{s_{NN}}=\sqrt{s}=5.02$TeV are measured with the ATLAS experiment at the LHC. The measurements are performed with $p$+Pb data recorded in 2013 with an integrated luminosity of 25nb${}^{-1}$ and $pp$ data recorded in 2015 with an integrated luminosity of 28pb${}^{-1}$. The $p$+Pb results are compared to $pp$ spectra, presented as a ratio of transverse momentum distributions in the two systems scaled by the number of binary nucleon-nucleon collisions, the nuclear modification factor $R_{p \mathrm{Pb}}$. The study of $R_\mathrm{pPb}$ allows a detailed comparison of the collision systems in different centrality intervals and in a wide range of transverse momentum. It is shown that the nuclear modification factor does not have any significant deviation from unity in the high transverse momentum region.