Spin polarization as a probe of hot QCD matter formed in ultrarelativistic collisions at the large hadron collider

Abstract

Understanding the nature of the fundamental building blocks of matter, quarks and gluons, under extreme conditions of temperature and density, is one of the primary goals of the two largest collider experiments in the world: the Large Hadron Collider (LHC) at CERN and the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The ALICE experiment at the LHC mainly focuses on investigating the formation and properties of the Quark-Gluon Plasma (QGP), a strongly interacting, deconfined, and locally thermalized state of quarks and gluons that exhibits collective behavior and is expected to be created in ultrarelativistic heavy-ion collisions. To probe this transient state of matter, QGP, several indirect signatures have been proposed, such as the presence of strangeness enhancement, suppression of quarkonia, jet quenching, collective flow, direct photons, and dilepton production. These observables provide strong evidence for the possible formation of QGP in heavy-ion collisions and are commonly referred to as the 1st-generation probes of the QGP.