PhD defence: Study of energy flow fluctuations within jets at heavy-ion collisions with ALICE

This dissertation investigates the behavior of the strong nuclear force - a fundamental force of nature - under extreme conditions. Using data from the ALICE experiment at CERN’s Large Hadron Collider (LHC), the study focuses on high-energy particle collisions that recreate environments like the early universe.

In proton-proton collisions, jets - narrow sprays of particles - are created when the protons’ inner components, called quarks and gluons, interact. These collisions provide a controlled environment to study the strong nuclear force. Since jets in proton-proton collisions are well understood, measurements in such collisions serve as an essential reference point for analyzing more complex interactions in heavy-ion collisions.

Heavy-ion collisions involve much larger nuclei, such as lead, and create dramatically different conditions. These collisions produce a Quark-Gluon Plasma, a state of matter where quarks and gluons, usually confined inside particles, move freely. This plasma interacts with jets as they pass through, causing jet quenching - a phenomenon where jets lose energy, and their structure is altered due to interactions with the plasma.

This research introduces a new method to measure how energy flows within jets, comparing results from proton-proton and heavy-ion collisions. In heavy-ion collisions, jets show energy loss and narrower energy profiles compared to proton-proton collisions. These differences reveal the plasma's effects on particle interactions.

By contrasting the two types of collisions, this study provides new insights into how the strong nuclear force operates in extreme environments, advancing our understanding of the universe’s earliest moments.