Sudakov suppression of jets in QCD media

TL;DR

This paper analyzes how dense QCD media suppress jets, revealing that jet quenching involves a factorized approach accounting for total color charge and Sudakov suppression of unresolved subjets, highlighting the role of color coherence.

Contribution

It introduces the jet collimator concept, showing how unresolved subjets lose energy coherently, and demonstrates the factorization of jet suppression into quenching and Sudakov factors.

Findings

Jet suppression factorizes into quenching and Sudakov suppression.

Color coherence reduces jet suppression compared to incoherent models.

Unresolved subjets lose energy coherently, affecting jet quenching predictions.

Abstract

We compute modifications to the jet spectrum in the presence of a dense medium. We show that in the large-$N_c$ approximation and at leading logarithmic accuracy the jet nuclear modification factor factorizes into a quenching factor associated to the total jet color charge and a Sudakov suppression factor which accounts for the energy loss of jet substructure fluctuations. This factor, called the jet collimator, implements the fact that subjets, that are not resolved by the medium, lose energy coherently as a single color charge, whereas resolved large angle fluctuations suffer more quenching. For comparison, we show that neglecting color coherence results in a stronger suppression of the jet nuclear modification factor.