2d DI-HADRON CORRELATION AT √SNN = 200 GeV USING THE STAR EXPERIMENT

Abstract

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab (BNL) in Long Island, New York, attempts to recreate the initial conditions at the birth of our universe. Heavy Au ions are accelerated up to 0.99995c and collided at √SNN = 200 GeV (center of mass energy per nucleon) in order to recreate the initial moments (~10−6s) after the Big Bang. The theory of Quantum Chromo Dynamics (QCD) predicts the formation of a primordial nuclear matter phase know as Quark Gluon Plasma (QGP) under these experimental conditions. This dissertation focuses on studying this QCD medium using data from the Solenoidal Tracker At RHIC (STAR) detector.

The study of two-dimensional two-particle correlations of emitted charged parti- cles contains valuable time integrated information of the dynamical QCD medium. Long range correlations between particles in angular and momentum space generally can be attributed to collective behavior not found in a superposition of elementary collisions. The focus of this thesis is to understand a novel, long-range correlation structure observed in pseudo-rapidity (∆η) as a function of <pT >. Data from √SNN = 200 GeV AuAu collisions are confronted with CuCu and pp collisions at the same energy to establish system size dependence. The interpretation is based on empirical models describing well established hydrodynamical collective flow phenomena and possible novel phenomena related to in medium parton fragmentation. The param- eters extracted from the model fit can be used to constrain medium properties such as the initial gluon density, the shear viscosity and the partonic energy transport coefficient.