Ratios of jet and hadron spectra at LHC energies: measuring high-$p_T$ suppression without a $pp$ reference

TL;DR

This paper evaluates methods to determine jet and hadron spectra ratios at different energies at the LHC, crucial for studying energy loss without a dedicated proton-proton reference, with high precision estimates for upcoming oxygen-oxygen collisions.

Contribution

It introduces and assesses techniques for computing spectra ratios at different energies without a pp baseline, aiding energy loss studies in future LHC runs.

Findings

Spectra ratio estimates agree within 4% for hadrons and 2% for jets.

Interpolated spectra provide accurate reference estimates.

Proposed OO/pp spectra ratio separates experimental and theoretical uncertainties.

Abstract

We analyze the reliability of several techniques for computing jet and hadron spectra at different collision energies. This is relevant for discovering energy loss in the upcoming oxygen-oxygen (OO) run at the LHC, for which a reference pp run is currently not planned. For hadrons and jets we compute the ratio of spectra between different pp collision energies in perturbative QCD, which can be used to construct a reference spectrum. Alternatively, it can be interpolated from measured spectra at nearby energies. We estimate the precision of both strategies for the spectra ratio relevant to the oxygen run, and conclude that the central values agree to 4% accuracy for hadrons and 2% accuracy for jets. Finally we propose taking the ratio of OO and pp spectra at different collision energies, which cleanly separates the experimental measurement and theoretical computation.