We will discuss the first momentum scale (kT) scan of the Lund Jet Plane (LJP) in heavy-ion collisions by CMS. The LJP is a two-dimensional representation of the phase space of emissions inside a jet constructed using iterative Cambridge-Aachen declustering. Its measurement in pp collisions allows to constrain the different ingredients of the parton shower and hadronization in a modular fashion. In heavy-ion collisions, the Quark Gluon Plasma is expected to affect the parton shower and modify the measured LJP relative to pp collisions. A kT scan of the Lund plane allows us to explore the scale dependence of the jet-QGP interactions. Our measurement was designed to test the validity of the factorisation between the early vacuum and QGP-induced stages of jet evolution in heavy ion collisions, which is an assumption of several jet quenching models.

In addition, we’ll discuss a new method that uses the LJP to improve the modelling in simulation of large-R multi-prong jets due to the decay of heavy resonances into multiple SM quarks. The method has interesting applications also for jets in heavy-ion collisions.

Refreshments will be served at 10h30