8th International Conference on New Frontiers in Physics (ICNFP 2019)

Classical excluded volume of loosely bound light (anti)nuclei and their chemical freeze-out in high energy nuclear collisions

28 Aug 2019, 18:00

30m

Room 1

Workshop on Physics at FAIR-NICA-SPS-BES/RHIC

Speaker

Prof. Kyrill Bugaev (BITP, Kiev, Ukraine)

Description

From the analysis of light (anti)nuclei multiplicities [1, 2] that were measured recently by the ALICE collaboration in Pb+Pb collisions at the center-of-mass collision energy √s =2.76 TeV [3] there arose a highly non-trivial question about the excluded volume of composite particles. Surprisingly, the hadron resonance gas model (HRGM) is able to perfectly describe the light (anti)nuclei multiplicities [1, 2] under various assumptions. For instance, one can consider the (anti)nuclei with a vanishing hard-core radius (as the point-like particles) or with the hard-core radius of proton, but the fit quality is the same for these assumptions. However, it is clear that such assumptions are unphysical. Hence we derived a new formula for the hard-core radius of a nuclei consisting of A baryons or antibaryons which does not lead to the hard-core radius expression R(A) = R(1) ∛A used in [2] recently for A>1. To implement a new relation into the HRMG we employ the induced surface tension concept [1, 4] and perform a thorough analysis of hadronic and (anti)nuclei multiplicities measured by the ALICE collaboration. The HRGM with the induced surface tension allows us to verify different assumptions on the values of hard-core radii and different scenarios of chemical freeze-out of (anti)nuclei. It is shown that the most successful description of hadrons can be achieved at the chemical freeze-out temperature of about Th=150 MeV, while the one for all (anti)nuclei is TA=168-172 MeV. Similar analysis is made for the 6-quark states suggested in [5] and their yields for the central high energy nuclear collisions are predicted.

1. K. A. Bugaev, V. V. Sagun, A. I. Ivanytskyi, I. P. Yakimenko, E. G. Nikonov, A.V. Taranenko and G. M. Zinovjev, Nucl. Phys. A 970, 133 (2018).

2. K. A. Bugaev, B. E. Grinyuk, A. I. Ivanytskyi, V. V. Sagun, D. O. Savchenko, G. M. Zinovjev, E. G. Nikonov, L. V. Bravina, E. E. Zabrodin, D. B. Blaschke, S. Kabana and A. V. Taranenko, arXiv:1812.02509v1 [hep-ph].

3. J. Adam et al. [ALICE Collaboration], Phys. Rev. C 93, no. 2, 024917 (2016).

4. V. V. Sagun, K. A. Bugaev, A. I. Ivanytskyi, I. P. Yakimenko, E. G. Nikonov, A.V. Taranenko, C. Greiner, D. B. Blaschke and G. M. Zinovjev, Eur. Phys. J. A 54, 100 (2018).

5. G. R. Farrar, arXiv:1708.08951v2 [hep-ph].