Discovering partonic rescattering in light nucleus collisions

TL;DR

This paper shows that oxygen-oxygen collisions at the LHC can effectively reveal partonic rescattering effects, with precise baseline calculations enabling the detection of energy loss signatures through charged hadron spectra.

Contribution

It introduces a method to identify partonic rescattering in light nucleus collisions using precise baseline calculations and charged hadron spectra measurements.

Findings

Baseline in the absence of rescattering known within 2% accuracy

Z-boson normalized nuclear modification factor has limited sensitivity

Charged hadron spectra can reveal partonic rescattering signals

Abstract

We demonstrate that oxygen-oxygen (OO) collisions at the LHC provide unprecedented sensitivity to parton energy loss in a system whose size is comparable to those created in very peripheral heavy-ion collisions. With leading and next-to-leading order calculations of nuclear modification factors, we show that the baseline in the absence of partonic rescattering is known with up to 2% theoretical accuracy in inclusive OO collisions. Surprisingly, a $Z$-boson normalized nuclear modification factor does not lead to higher theoretical accuracy within current uncertainties of nuclear parton distribution functions. We study a broad range of parton energy loss models and we find that the expected signal of partonic rescattering can be disentangled from the baseline by measuring charged hadron spectra in the range $20\,\text{GeV}<p_T<100\,\text{GeV}$