Heavy ion collisions at the LHC and RHIC produce a quark gluon plasma (QGP), in which quarks and gluons are deconfined into an extended medium. This “fourth phase” of matter is also believed to have been the first material phase of the universe following the Big Bang. In experiment, high energy partons scatter at short time scales and may subsequently lose energy, or are “quenched”, via interactions with the QGP. We approximate these high energy partons by “jets,” the combined four-momenta of collimated sprays of final state particles, and use these jets to probe for QGP formation and properties. We present semi-inclusive jet measurements from √sNN = 200GeV proton+gold (p+Au) collisions recorded by STAR at RHIC in 2015, which are the first semi-inclusive jet measurements for small system collisions (p/d/He3+A) at RHIC kinematics . These measurements demonstrate that, within the precision allowed by statistics and systematic uncertainties, there is no jet quenching in these small system collisions. We also present measurements of significant, and previously unexpected, correlations between the semi-inclusive jet momentum spectra and collisional event activity. We demonstrate how these results support the conclusion that correlations between jet formation and EA in small systems offer an opportunity to probe not the QGP, but rather the early initial stages of these collisions.
Thesis Advisor: Helen Caines (helen.caines@yale.edu)
Please contact Stacey Watts (stacey.watts@yale.edu) for zoom information
*Please note this event has moved from WLC-245 to WL-216*