# Jet splitting functions in the vacuum and in a QCD medium

## TL;DR

This paper presents the first resummed calculation of jet splitting functions in heavy-ion collisions, revealing significant modifications for heavy flavor jets and offering new insights into in-medium parton shower dynamics.

## Contribution

It introduces a unified theoretical framework for jet splitting functions in vacuum and medium, including heavy flavor jets, with novel predictions on mass-dependent modifications.

## Key findings

- Light jet splitting functions agree with RHIC and LHC data.
- Heavy flavor jets show stronger medium modification.
- Provides a new approach to constrain mass effects in parton showers.

## Abstract

The two-prong structure related to the leading subjets inside a reconstructed jet opens new avenues toward precision constraints on the in-medium modification of parton showers. In this talk, we present the first resummed calculation of the soft-dropped groomed momentum sharing distribution, or the jet splitting function, in heavy-ion collisions for both light jets and heavy flavor tagged jets. Existing light jet splitting function data from the STAR experiment at RHIC and the CMS experiment at LHC can be understood in the unified framework of soft-collinear effective theory with Glauber gluon interactions. For heavy flavor jets, very interestingly, the momentum sharing distribution of b-tagged jets is more strongly modified in comparison to the one for light jets, which provides a novel handle on mass corrections to in-medium parton showers that are at present difficult to constraint using inclusive heavy meson production.