Resummation of Jet Shapes and Extracting Properties of the Quark-Gluon Plasma

TL;DR

This paper develops a theoretical framework using soft-collinear effective theory to calculate and resum jet shape modifications in proton-proton and lead-lead collisions, providing insights into the properties of the quark-gluon plasma.

Contribution

It introduces a novel application of SCET with Glauber gluons to compute jet shape modifications in medium, including resummation at NLL accuracy and leading-order medium effects.

Findings

Good agreement with CMS jet shape measurements

Resummation reduces theoretical uncertainties

Provides a tool to extract QGP properties

Abstract

Understanding the properties of the quark-gluon plasma (QGP) that is produced in ultra-relativistic nucleus-nucleus collisions has been one of the top priorities of the heavy ion program at the LHC. Energetic jets are produced and subsequently quenched in the collisions. Such jet quenching phenomena provide promising tools to probe the medium properties by studying the modification of jets due to the medium interactions. Significant modifications of jet shapes have been measured. In this talk we focus on the calculation of jet shapes in both proton-proton and lead-lead collisions using soft-collinear effective theory (SCET), with Glauber gluon interactions in the medium. Large logarithms in jet shapes are resummed at next-to-leading logarithmic (NLL) accuracy by the renormalization-group evolution between hierarchical jet scales. The medium interactions contribute as power corrections, and we calculate the modification of jet shapes at leading order in opacity with the static QGP model. Preliminary results are presented with good agreement with the recent CMS jet shape measurements.