March 19, 2018, 12:00 PM, 112W
Zhenyu Chen (Rice)
Quark-Gluon Plasma at the Smallest Scales

In ultra-relativistic collisions of large, heavy nuclei (e.g. Au or Pb), a new state of nuclear matter consisting of liberated quarks and gluons is formed at a temperature of trillion Kelvins. This state of matter, commonly referred to as Quark Gluon Plasma (QGP), was discovered and confirmed at the Relativistic Heavy Ion Collider (BNL) and the Large Hadron Collider (CERN). The QGP was found to exhibit collective behavior and flow as a nearly 'perfect' fluid. The elementary collision systems such as proton-proton (pp) or proton-nucleus (pA), which were thought to be too small and dilute to form a QGP, were treated as references in understanding the perfect fluidity in large heavy ion systems. Surprisingly, evidence for collective effects and QGP formation has been revealed in those smallest collisions in the recent years, when looking at rare events releasing large number of particles. In this talk, I will go over key findings related to the possible QGP formation in pp and pA systems. Their implications to the paradigm of heavy ion physics will also be discussed.



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