Higher moments of net kaon multiplicity distributions at RHIC energies for the search of QCD Critical Point at STAR

摘要

In this paper we report the measurements of the various moments mean (M), standard deviation (σ), skewness (S) and kurtosis (k) of the net-Kaon multiplicity distribution at mid rapidity in Au+Au collisions from √s_(NN) =7.7 to 200 GeV in the STAR experiment at RHIC in an effort to locate the critical point in the QCD phase diagram. These moments and their products are related to the thermodynamic susceptibilities of conserved quantities such as net baryon number, net charge, and net strangeness as also to the correlation length of the system. A non-monotonic behaviour of these variables indicate the presence of the critical point. In this work we also present the moment products Sσ and κσ2 of net-Kaon multiplicity distribution as a function of collision centrality and energy. The energy and the centrality dependence of higher moments of net-Kaons and their products have been compared with its Poisson expectation and with simulations from AMPT which does not include the critical point. From the measurement at all seven available beam energies, we find no evidence for a critical point in the QCD phase diagram.