Soft and Collective Particle Generator for a Better Understanding of Heavy Ion Background in Jet Studies

At the Large Hadron Collider (LHC) in Europe and the Relativistic Heavy Ion Collider in New York, nuclei are made to collide at near the speed of light. These collisions generate a new phase of nuclear matter: a Quark Gluon Plasma (QGP). The QGP differs from ordinary nuclear matter because its elementary constituents are strongly interacting quarks and gluons as opposed to hadrons. Quarks and gluons in the colliding nuclei often scatter off of each other with high momentum transfer. These scatterings produce collimated streams of hadrons called jets. Jets are modified as they pass through the QGP and these modifications can be studied to determine the properties of the medium. The main difficulty in jet measurements in heavy-ion collisions is dealing with large, uncorrelated background of hadrons. This background is the result of the expansion and cooling of the short lived QGP into a multitude of hadrons. We generate a data-driven background for jets based on measurements of soft charged hadron transverse momentum spectra and charged hadron azimuthal flow at the LHC to better understand the effects of this background. We discuss how this heavy ion background generator can be used to understand the modification of jets by the background in heavy ion collisions.