Bochum 2018 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 9: Heavy Ion Collisions and QCD Phases II
HK 9.3: Talk
Monday, February 26, 2018, 17:15–17:30, HZO 60
The effect of finite particle number sampling on baryon number fluctuations — •Jan Steinheimer1 and Volker Koch2 — 1Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main, Germany — 2Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
In this talk we discuss the effects of finite particle number sampling on the net baryon number cumulants, extracted from fluid dynamical simulations of nuclear collisions. The commonly used finite particle number sampling procedure introduces an additional Poissonian (or multinomial if global baryon number conservation is enforced) contribution which increases the extracted moments of the baryon number multiplicity distribution. If this procedure is applied to a fluctuating fluid dynamics framework one severely overestimates the actual cumulants. It will be shown that the sampling of so called test-particles suppresses the additional contribution to the moments by at least one power of the number of test-particles. The method will be demonstrated for a numerical fluid dynamics simulation that includes the effects of spinodal decomposition due to a first order QCD phase transition in heavy ion collisions. Furthermore, in the limit where anti-baryons can be ignored, we derive analytic formulas which capture exactly the effect of particle sampling on the baryon number cumulants. These formulas may be used to test the various numerical particle sampling algorithms.
This talk is based on: J.Steinheimer and V.Koch, Phys. Rev. C 96, no. 3, 034907 (2017).