Medium-modified Jet Shapes and other Jet Observables from in-medium Parton Shower Evolution

TL;DR

This paper uses Monte Carlo simulations to predict how jet shapes and other observables are modified by the medium in heavy-ion collisions, providing insights into in-medium parton shower evolution at RHIC and LHC energies.

Contribution

It introduces predictions for medium-modified jet observables using the YaJEM MC code across different interaction scenarios, aligning with high P_T hadron suppression data.

Findings

Jet shapes are significantly altered by medium effects.

Predictions are consistent with existing high P_T suppression data.

Analysis covers energies relevant to RHIC and LHC.

Abstract

The suppression of large transverse momentum hadrons in heavy-ion (A-A) collisions as compared to their scaled expectation from proton-proton collisions due to the interaction of hard partons with the hot and dense QCD medium in A-A collisions is experimentally a well established phenomenon. Focusing on leading hadrons produced in hard processes, the medium effect appears as energy loss. Beyond that, the question is how the lost energy is redistributed in the medium. With increased experimental statistics and most importantly the kinematic range of the LHC, studying the properties of full jets rather than leading hadrons is becoming feasible. On the theory side, analytic models and Monte-Carlo (MC) codes for in-medium shower evolution are being developed to describe jets in the medium. In this paper, expectations for medium-modified jet observables, the jet shapes, the thrust distribution and the n-jet fraction, are computed with the MC code YaJEM for various scenarios of the parton-medium interaction which all are consistent with high P_T hadron suppression data. The computation is done at 20 and 100 GeV jet energy, corresponding to probing typical RHIC and LHC kinematics, and the possibility to make an unbiased measurement of the observables is discussed.