TITLE : Nearly "perfect" quark-gluon droplet at the smallest scales
ABSTRACT :
In high energy collisions of large, heavy nuclei (e.g., Au or Pb), a new state of matter consisting of liberated quarks and gluons is formed at a temperature of a few trillion Kelvins. This "Quark-Gluon Plasma" (QGP), discovered at the Relativistic Heavy Ion Collider (BNL) and the Large Hadron Collider (CERN, Switzerland), is found to exhibit amazing collective behavior as a nearly "perfect" fluid, which flows with close-to-zero viscous dissipation. It was thought that elementary collision systems like proton-proton (pp) or proton-nucleus (pA) are too small and dilute to form a QGP fluid so they were often treated as a reference in understanding the emergence of perfect fluidity in large heavy ion systems. Surprisingly, in recent years, evidence for collective effects and QGP formation has also been revealed in those smallest collisions, when looking at a fraction of rare events releasing the largest number of particles. In this talk, I will describe key findings related to the possible formation of the tiniest QGP fluid in pp and pA systems, and discuss their implications to the standard paradigm of heavy ion physics, as well as new opportunities opened up in studying emergent Quantum Chromodynamics phenomena under extreme conditions.
ABOUT THE SPEAKER :
Prof. Prabhat Pujahari received his Ph.D. in experimental particle and nuclear physics at IIT Bombay in 2012. Following a postdoc position at Wayne State University, USA and CERN, Geneva working on the first relativistic heavy ion physics program at the LHC, he joined the IITM physics faculty in 2016. Prof. Pujahari's interest focuses on understanding emergent behaviors in strong nuclear forces under extreme conditions. Prof. Pujahari has been a leader of the CMS heavy ion program since 2016, serving as co-convener of the group. His group led to a surprising discovery of quark-gluon plasma in proton-proton and proton-nucleus collisions - the systems considered to be a reference to HIN collisions.
MEETING DETAILS :
Speaker: Prof. Prabhat Pujahari, IIT Madras, Chennai
Venue: A1 NKN Hall, South Campus, IIT Mandi
Date and Time: April 24, 2026, Friday at 12 Noon