Quantum simulation of in-medium QCD jets: momentum broadening, gluon production, and entropy growth

TL;DR

This paper uses quantum simulations to model the real-time evolution of QCD jets in a medium, revealing effects on momentum broadening, gluon production, and entropy growth, advancing understanding of jet-medium interactions.

Contribution

It extends previous quantum simulations of jet evolution by including gluon production and analyzes entropy growth and medium effects in a quantum framework.

Findings

Sizable sub-eikonal effects in momentum broadening.

Small medium-induced modifications to gluon emission.

Entropy grows linearly for bare quark, super-linearly with gluon emission.

Abstract

Jets provide one of the primary probes of the quark-gluon plasma produced in ultrarelativistic heavy ion collisions and the cold nuclear matter explored in deep inelastic scattering experiments. However, despite important developments in the last years, a description of the real-time evolution of QCD jets inside a medium is still far from being complete. In our previous work, we have explored quantum technologies as a promising alternative theoretical laboratory to simulate jet evolution in QCD matter, to overcome inherent technical difficulties in present calculations. Here, we extend our previous investigation from the single particle $|q\rangle$ to the $|q\rangle+|qg\rangle$ Fock space, taking into account gluon production. Based on the light-front Hamiltonian formalism, we construct a digital quantum circuit that tracks the evolution of a multi-particle jet probe in the presence of a medium described as a stochastic color field. Studying the momentum broadening of the jet state, we observe sizable sub-eikonal effects by comparing to eikonal estimates. We also study the medium-induced modifications to the gluon emission probability, which exhibit small corrections compared to the vacuum splitting function. In addition, we study the time evolution of the von-Neumann entropy associated with the quark component; we find that the exponential of the entropy grows linearly in time for the bare quark but super-linearly when taking into account gluon emission.