Faculty of Physics - University of Bucharest

UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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2024-11-23 17:37

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Conference: Bucharest University Faculty of Physics 2017 Meeting

Section: Nuclear and Elementary Particles Physics

Title:

Predictions over some possible phase transitions in new formed nuclear matter in Au-Au ultrarelativistic nuclear collisions in CBM experiment at FAIR-GSI

Authors:

Nicolae George ȚUȚURAȘ(1), Alexandru JIPA(1), Tiberiu EȘANU(2,1), Adam JINARU(2), and Marius CĂLIN(1)

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Affiliation:

1) University of Bucharest, Faculty of Physics, Bucharest - Romania

2) National Institute for Physics and Nuclear Engineering, Bucharest-Romania

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Keywords:

CBM, phase transition, mixed phase, hadron gas, QGP

Abstract:

The CBM experiment at FAIR GSI is motivated by the study of the nuclear matter state equation for high baryon densities, and the search of phase transitions. In the case of our work, the 10-13 A GeV and 18-21 A GeV intervals show interesting results, which suggest possible phase transitions in the CBM experiment compatible range of energies, between 6 and 28 A GeV. Using the UrQMD and AMPT generators, which were integrated in the YaPT system of the Research Center „Nuclear Matter in Extreme Conditions” of the Faculty of Physics, University of Bucharest, repetitive phenomena can be identified in our results presented next. Our numerical calculations highlight fluctuations of the K-/K+ and anti-p/p ratios, which are collision centrality dependent. In particular, a „change of order” takes place, i.e. a ratio value growth specific to a centrality, compared to the ratio value calculated for the other centrality, much more visible in the specified ranges of energies. There's another very important thing concerning the centrality dependence: for 0.5 < y < 1.4 and 0 < y < 0.8 , one can notice that for the second centrality, 20-40%, the K-/K+ ratio is many times higher than that for the previous centrality, in good agreement with the HADES experiment. On the other hand, the increase of these ratios with increasing collision energy of heavy ions is confirmed by experiments, and this behaviour is also seen in our results. Note that, in contrast to this general trend, we get some local trends of equality (plateau) and quasi-drops of the ratios, in the 10-13 A GeV and 18-21 A GeV ranges, presented for the above two centralities and rapidities. These suggest the switching to a mixed phase, for a fraction of time, and by this we understand a coexistence of quark-gluon plasma (QGP) and hadronic gas regions, which can result in visible effects in flow excitation function.

Acknowledgement:

Thanks to the Institute of Atomic Physics for financial support awarded in the program Romania-FAIR (grant F09/30.VI.2014, grant F09/16.IX.2017).