Observations from collisions of heavy-ion at relativistic energies have established the formation of a new phase of matter, Quark Gluon Plasma (QGP), a deconfined state of quarks and gluons 1 in a specific region of the temperature versus baryonic chemical potential phase diagram of strong interactions. A program to study the features of the phase diagram, such as a possible critical point, by varying the collision energy (√sNN), is performed at the Relativistic Heavy-Ion Collider (RHIC) facility. Non-monotonic variation with √sNN of moments of the net-baryon number distribution, related to the correlation length and the susceptibilities of the system, is suggested as a signature for a critical point 2,3. We report the first evidence of a non-monotonic variation in kurtosis × variance of the net-proton number (proxy for net-baryon number) distribution as a function of √sNN with 3.0σ significance, for head-on (central) gold-on-gold (Au+Au) collisions measured using the STAR detector 4 at RHIC. Non-central Au+Au collisions and models of heavy-ion collisions without a critical point show a monotonic variation as a function of √sNN.
|Original language||English (US)|
|State||Published - Jan 9 2020|
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