Jul 9 – 15, 2017
Victor J. Koningsberger building
Europe/Amsterdam timezone

Resonances in a sudden chemical freeze-out model

Jul 14, 2017, 5:05 PM
BBG 161

BBG 161

oral presentation Hadron resonances Parallel Resonances


Viktor Begun (UJK)


A chemical non-equilibrium model with a single freeze-out appeared to be rather successful in describing the LHC ALICE data at 2.76 TeV for various particles [1,2]. The pT spectra of pions, kaons, protons, $K^*(892)^0$ and the $\phi(1020)$ are described by the same hubble-like freeze-out hyper-surface that has only one parameter for the slope of the spectra – the ratio of the freeze-out time to the freeze-out radius [1,2]. This is very surprising for the $K^*(892)^0$ and the $\phi(1020)$, because the first one is short leaving, while the second one is long living. The description of both of them may question the necessity of the long re-scattering phase, which is also successfully used to describe the ALICE data [3]. It may also indicate that the non-equilibrium, as implemented in [1,2], may effectively include the re-scattering in the non-equilibrium chemical potentials. It is important to differentiate between the equilibrium with the re-scattering, and the single sudden freeze-out in the non-equilibrium, because the non-equilibrium also leads to pion condensation [4].

A good test for the non-equilibrium single freeze-out scenario [1,2] is the comparison to different resonances, especially strange resonances, because this scenario requires a special relation between the strange and the non-strange chemical potentials, depending on the quark content of a resonance. The heavy $\Lambda$ $\Xi$ and $\Omega$ can be still described by the non-equilibrium very well, if one assumes a smaller slope for them [2]. This introduces the dependence on the mass of the resonance, but is also supported by smaller flow of heavy particles in other approaches, see e.g. [4].

In this work, the predictions for the mean multiplicities and the pT spectra of various strange resonances are made, including the $\rho(770)$, $\Lambda(1520)$, $\Xi(1530)$ and $\Sigma(1385)$.


[1] V. Begun, W. Florkowski and M. Rybczynski,
Explanation of hadron transverse-momentum spectra in heavy-ion collisions at $\sqrt{s_{NN}}=$ 2.76 TeV within chemical non-equilibrium statistical hadronization model,
Phys. Rev. C 90 (2014) no.1, 014906 [arXiv:1312.1487 [nucl-th]].

[2] V. Begun, W. Florkowski and M. Rybczynski,
Transverse-momentum spectra of strange particles produced in Pb+Pb collisions at $sqrt{s_{rm NN}}=2.76$ TeV in the chemical non-equilibrium model,
Phys. Rev. C 90 (2014) no.5, 054912 [arXiv:1405.7252 [hep-ph]].

[3] A.G. Knospe, C. Markert, K. Werner, J. Steinheimer and M. Bleicher,
Hadronic resonance production and interaction in partonic and hadronic matter in the EPOS3 model with and without the hadronic afterburner UrQMD,
Phys. Rev. C 93 (2016) no.1, 014911 [arXiv:1509.07895 [nucl-th]].

[4] V. Begun,
Fluctuations as a test of chemical non-equilibrium at the LHC,
Phys. Rev. C 94 (2016) no.5, 054904 [arXiv:1603.02254 [nucl-th]].

[5] I. Melo and B. Tomasik,
Reconstructing the final state of Pb+Pb collisions at $sqrt{s_{NN}=2.76}$ TeV,
J. Phys. G 43 (2016) no.1, 015102, [arXiv:1502.01247 [nucl-th]].

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