# Quark Matter 2014 - XXIV International Conference on Ultrarelativistic Nucleus-Nucleus Collisions

19-24 May 2014
darmstadtium
Europe/Zurich timezone

## The onset of pion condensation in heavy-ion collisions at the LHC energies

20 May 2014, 16:30
2h
spectrum (darmstadtium)

### spectrum

#### darmstadtium

Board: J-01
Poster Thermodynamics and Hadron Chemistry

### Speaker

Dr Viktor Begun (UJK)

### Description

Statistical models of hadron production have become one of the cornerstones of our understanding of ultra-relativistic heavy-ion collisions [1]. However, the measured proton abundances in Pb+Pb collisions at sqrt(sNN) = 2.76 TeV at LHC do not agree with the most common versions of the thermal models. Besides the proton anomaly, the same LHC data exhibits the low-transverse-momentum enhancement of pion spectra by about 25-50% with respect to the predictions of various thermal and hydrodynamic models [2]. In the recent work [3] we connect the proton anomaly with the pion enhancement effect and show that the two problems may be solved naturally within the statistical model which assumes chemical non-equilibrium at the freeze-out and a special combination of freeze-out geometry and flow - the Krakow single-freeze-out model in the Monte-Carlo version implemented in THERMINATOR [4]. We find a remarkable agreement between our model and the measured transverse-momentum spectra of pions and kaons. Although the protons are not included in the fit, our model explains well their spectrum, in addition to their yield. We also find a satisfactory description of hyperons with the same parameters. Correct description of the low-transverse-momentum enhancement of pions within our model suggests that it may be interpreted as a signature of the onset of pion condensation in ultra-relativistic heavy-ion collisions at the LHC energies. This is so, since the freeze-out conditions in the model are very close to the pion condensation point. [1] P. Braun-Munzinger, D. Magestro, K. Redlich, J. Stachel, Phys. Lett. B 518, 41 (2001). [2] B. Abelev et al. [ALICE Collaboration], Phys. Rev. Lett. 109, 252301 (2012); Phys. Rev. C 88, 044910 (2013). [3] V. Begun, W. Florkowski, M. Rybczynski, arXiv:1312.1487 [nucl-th]. [4] M. Chojnacki, A. Kisiel, W. Florkowski and W. Broniowski, Comput. Phys. Commun. 183, 746 (2012).

### Primary author

Dr Viktor Begun (UJK)

### Co-authors

Maciej Rybczynski (Jan Kochanowski University (PL)) Wojciech Florkowski (Institute of nuclear Physics, Krakow)

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