Medium-evolved fragmentation functions

TL;DR

This paper develops an improved DGLAP-based model for jet quenching in heavy-ion collisions by incorporating medium effects into splitting probabilities, ensuring energy-momentum conservation and coherence between vacuum and medium contributions.

Contribution

It introduces a unified approach combining medium and vacuum splittings within DGLAP, including energy-momentum conservation and virtuality evolution, improving upon traditional independent emission models.

Findings

The model reproduces observed jet suppression in heavy-ion collisions.

It aligns with transport coefficient values from quenching weights.

The formalism reduces to standard DGLAP at high energies.

Abstract

Medium-induced gluon radiation is usually identified as the dominant dynamical mechanism underling the {\it jet quenching} phenomenon observed in heavy-ion collisions. In its actual implementation, multiple medium-induced gluon emissions are assumed to be independent, leading, in the eikonal approximation, to a Poisson distribution. Here, we introduce a medium term in the splitting probabilities so that both medium and vacuum contributions are included on the same footing in a DGLAP approach. The improvements include energy-momentum conservation at each individual splitting, medium-modified virtuality evolution and a coherent implementation of vacuum and medium splitting probabilities. Noticeably, the usual formalism is recovered when the virtuality and the energy of the parton are very large. This leads to a similar description of the suppression observed in heavy-ion collisions with values of the transport coefficient of the same order as those obtained using the {\it quenching weights}.