Heavy--quark momentum correlations as a sensitive probe of thermalization

TL;DR

This paper explores using heavy-quark azimuthal correlations as a novel probe to assess the degree of thermalization in the quark-gluon plasma formed during high-energy nuclear collisions, employing PYTHIA simulations for baseline comparisons.

Contribution

It introduces a method to measure heavy-quark correlations as an indicator of thermalization, highlighting the potential of azimuthal correlation modifications as a signal.

Findings

PYTHIA simulations establish baseline correlations in p-p collisions.

Azimuthal correlations are sensitive to thermalization effects.

The two-particle transverse momentum correlator effectively measures these correlations.

Abstract

In high-energy nuclear collisions the degree of thermalization at the partonic level is a key issue. Due to their large mass, heavy-quarks and their participation in the collective flow of the QCD medium constitute a powerful tool to probe thermalization. We propose measuring azimuthal correlations of heavy-quark hadrons and products from their semi-leptonic decay. Modifications or even the complete absence of initially, e.g. in p-p collisions, existing azimuthal correlations in Pb-Pb collisions might indicate thermalization at the partonic level. We present studies with PYTHIA for p-p collisions at the top LHC energy using the two-particle transverse momentum correlator ${<\overline{\Delta}p_{t,1}\overline{\Delta}p_{t,2}>}$ as a sensitive measure of azimuthal correlations.