21-23 December 2020
Online meeting
Europe/Kiev timezone

Connecting fluctuation measurements in heavy ion collisions and grand canonical susceptibilities: global conservation effects

21 Dec 2020, 10:50
20m
Online meeting

Online meeting

Oral talk Physics of Nuclei and Elementary Particles Physics of Nuclei and Elementary Particles

Speaker

Roman Poberezhnyuk (Bogolyubov Institute for Theoretical Physics of the National Academy of Sciences of Ukraine)

Description

We present the relation between cumulants of a conserved charge measured in a subvolume of a thermal system and the corresponding grand-canonical susceptibilities, taking into account exact global conservation of all QCD charges. The derivation is presented for an arbitrary equation of state, with the assumption that the subvolume is sufficiently large to be close to the thermodynamic limit. Our framework – the subensemble acceptance method (SAM) – quantifies the effect of global conservation laws and is an important step toward a direct comparison between cumulants of conserved charges measured in central heavy ion collisions and theoretical calculations of grand-canonical susceptibilities, such as lattice QCD. We show that the global conservation effects cancel out in any ratio of two second order cumulants, in any ratio of two third order cumulants, as well as in a ratio of strongly intensive measures Σ and ∆ involving any two conserved charges, making all these quantities particularly suitable for theory-to-experiment comparisons in heavy-ion collisions. We also show that the same cancellation occurs in correlators of a conserved charge, like the electric charge, with any non-conserved quantity such as net proton or net kaon number. The main results of the SAM are illustrated in the framework of the hadron resonance gas model. We also elucidate how net-proton and net-Λ fluctuations are affected by conservation of electric charge and strangeness in addition to baryon number.

Primary author

Roman Poberezhnyuk (Bogolyubov Institute for Theoretical Physics of the National Academy of Sciences of Ukraine)

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