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arXiv · 1510.05519

Net-proton number kurtosis and skewness in nuclear collisions: Influence of deuteron formation

Zuzana Feckova·Jan Steinheimer·Boris Tomasik·Marcus Bleicher
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Abstract

We explore the influence of deuteron formation in the late stage of nucleus-nucleus reactions on the fluctuations observed in the final net-proton yields around midrapidity. At each investigated energy, the produced (anti-)proton yield at chemical freeze-out is assumed to fluctuate according to a Poisson distribution and in each event the probability for deuteron formation by coalescence is proportional to $(dN_{\mathrm{proton}}/dy)^2$. The protons that are then clustered in deuterons are usually not included in the experimental measurement of the net-proton fluctuations, therefore, we subtract these clustered protons from the final state proton number for the calculation of the net-proton fluctuations (the same is done in the anti-proton sector). Due to the non-linear deuteron formation probability the resulting distribution is not a Skellam distribution, but shows the interesting feature of a decrease in the kurtosis $κσ^2$ and a local maximum in the skewness $S σ$ observables as the collision energy decreases.

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Zuzana Feckova, Jan Steinheimer, Boris Tomasik, Marcus Bleicher. 2015-10-19. Net-proton number kurtosis and skewness in nuclear collisions: Influence of deuteron formation. https://doi.org/10.1103/physrevc.92.064908

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