Speaker
Description
It has long been understood that non-monotonic variation of non-Gaussian cumulants of particle multiplicities as a function of decreasing collision energy and, hence, increasing baryon chemical potential $\mu_B$ can yield tell-tale signatures of the presence of a possible critical point in the QCD phase diagram. In this talk, we shall present quantitative estimates for the magnitude and $\mu_B$-dependence of the skewness and kurtosis of the proton multiplicity as a function of the separation $\Delta T$ between the temperature at a critical point and at freezeout. These provide a modern update of estimates first attempted in [1], for the first time including the effects of the change in the sign of the critical contribution to the kurtosis discovered in [2] in a way that incorporates the mapping between the universal physics around an Ising critical point onto the QCD phase diagram [3,4].
Several of us have recently quantified the reduction in the magnitude of the Gaussian cumulant of the proton multiplicity relative to equilibrium expectations, arising because both critical slowing down and baryon number conservation limit the growth of critical fluctuations [5]. In this talk, we describe how the dynamics in the critical regime (including critical slowing down and baryon number conservation) limit the growth of the non-Gaussian cumulants. It has been understood since they were first proposed as signatures of a critical point that dynamical effects make the actual cumulants much smaller than they would be in equilibrium; for the first time, we estimate how much smaller. We close by using the newly developed maximum entropy freezeout procedure [6] to make estimates of the magnitude of the skewness and kurtosis of proton multiplicity that can be expected in RHIC BES data if nature places a critical point near where these collisions freeze out.
[1] Athanasiou, Rajagopal, Stephanov, arXiv:1006.4636.
[2] Stephanov, arXiv: 1104.1627.
[3] Parotto et al, arXiv:1805.05249.
[4] Karthein et al, arXiv:2103.08146.
[5] Pradeep, Rajagopal, Stephanov and Yin, arXiv:2204.00639.
[6] Pradeep, Stephanov, arXiv:2211.09142.
| Category | Theory |
|---|
