Eur. Phys. J. C (2015) 75: 573
https://doi.org/10.1140/epjc/s10052-015-3775-0

Regular Article - Theoretical Physics

Impact of resonance regeneration and decay on the net proton fluctuations in a hadron resonance gas

¹ Department of Physics, Duke University, Durham, NC, 27708-0305, USA
² Frankfurt Institute for Advanced Studies (FIAS), Ruth-Moufang-Str. 1, 60438, Frankfurt am Main, Germany
³ Department of Physics, North Carolina State University, Raleigh, NC, 27695, USA
⁴ Dipartimento di Fisica, Università degli Studi di Torino and INFN, Sezione di Torino, via Pietro Giuria 1, 10125, Turin, Italy
⁵ Department of Physics, University of Houston, Houston, TX, 77204, USA

^* e-mail: marlene.nahrgang@phy.duke.edu

Received: 21 July 2015
Accepted: 5 November 2015
Published online: 1 December 2015

Abstract

We investigate net proton fluctuations as important observables measured in heavy-ion collisions within the hadron resonance gas (HRG) model. Special emphasis is given to effects which are a priori not inherent in a thermally and chemically equilibrated HRG approach. In particular, we point out the importance of taking into account the successive regeneration and decay of resonances after the chemical freeze-out, which lead to a randomization of the isospin of nucleons and thus to additional fluctuations in the net proton number. We find good agreement between our model results and the recent STAR measurements of the higher-order moments of the net proton distribution.