Critical versus spurious fluctuations in the search for the QCD critical point

TL;DR

This paper investigates the potential experimental signatures of the QCD critical point by analyzing fluctuations in pion production, considering realistic experimental uncertainties and plasma conditions.

Contribution

It introduces Monte Carlo simulations to assess the viability of fluctuation-based signatures of the QCD critical point under realistic heavy ion collision conditions.

Findings

Fluctuation signals are significantly attenuated by experimental uncertainties.

Event-by-event moments of pions can serve as potential signatures.

Realistic collision conditions diminish the expected critical signals.

Abstract

The neighborhood of the QCD chiral critical point is characterized by intense fluctuations of the chiral field which could, in principle, generate pronounced experimental signatures. However, experimental uncertainties which are inherent to heavy ion collisions, as well as the modest size and duration of the formed plasma, will severely attenuate these signatures. Using Monte Carlo techniques, we study second-order event-by-event moments of pions as a prototype for signatures of the chiral critical point based on the enhancement of the correlation length and event-by-event analysis. We test their viability against some realistic ingredients, similar to the ones found in the RHIC Beam Energy Scan program.