Beam energy dependence of moments of the net-charge multiplicity distributions in Au+Au collisions at RHIC

Adamczyk, L. and Adkins, J. K. and Agakishiev, G. and Aggarwal, M. M. and Ahammed, Z. and Alekseev, I. and Alford, J. and Anson, C. D. and Aparin, A and Arkhipkin, D. and Aschenauer, E. C. and Averichev, G. S. and Balewski, J. and Banerjee, A. and Barnovska, Z. and Beavis, D. R. and Bellwied, R. and Bhasin, A. and Bhati, A. K. and Bhattarai, P. and Bichsel, H. and Bielcik, J. and Bielcikova, J. and Bland, L. C. and Bordyuzhin, I. G. and Borowski, W. and Bouchet, J. and Brandin, A. V. and Brovko, S. G. and Bultmann, S. and Vértesi, Róbert (2014) Beam energy dependence of moments of the net-charge multiplicity distributions in Au+Au collisions at RHIC. PHYSICAL REVIEW LETTERS, 113 (9). ISSN 0031-9007

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Abstract

We report the first measurements of the moments — mean (M ), variance (σ2), skewness (S) and kurtosis (κ) — of the net-charge multiplicity distributions at mid-rapidity in Au+Au collisions at seven energies, ranging from √sNN = 7.7 to 200 GeV, as a part of the Beam Energy Scan program at RHIC. The moments are related to the thermodynamic susceptibilities of net-charge, and are sensitive to the location of the QCD critical point. We compare the products of the moments, σ2/M , Sσ and κσ2 with the expectations from Poisson and negative binomial distributions (NBD). The Sσ values deviate from Poisson and are close to NBD baseline, while the κσ2 values tend to lie between the two. Within the present uncertainties, our data do not show non-monotonic behavior as a function of collision energy. These measurements provide a valuable tool to extract the freeze-out parameters in heavy-ion collisions by comparing with theoretical models.

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