Seminar in Hadronic Physics

Event by event azimuthal correlations and flow at the LHC

Anthony Timmins

University of Houston

Relativistic heavy-ion collisions aim to create the Quark-Gluon Plasma (QGP), a unique state of matter where quarks and gluons can move freely over large volumes in comparison to the typical size of a hadron. It is believed that the universe temporally existed in such a state shortly after the big bang, where the temperatures needed for this transition are roughly 100,000 times bigger than the temperature at the center of the Sun. Experimental data collected over the past decade at the Relativistic Heavy Ion Collider (RHIC) at BNL have provided evidence that the QGP has been created in the lab. Since 2010, the Large Hadron Collider at the CERN laboratory has successfully collided Pb-Pb ions at the highest ever energies.

Measurements of azimuthal anisotropies at these energies have demonstrated strong fluctuations in the initial state, which may have a variety of important implications and uses. I will review techniques to select events with large (or small) azimuthal anisotropies, and discuss what can be learnt by studying such events. I will also discuss unfolding methods, which can be used to obtain azimuthal flow probability distributions. These distributions can be compared to models of the initial conditions (e.g. Glauber, Color Glass Condensate) and will provide strong constraints. These constraints are needed to determine the key transport properties of the QGP, such as the ratio of shear viscosity to entropy, and opacity.