Evolution of midrapidity average transverse momentum of pions, kaons, protons and antiprotons in Au þ Au collisions in ðsnnÞ1/2 = 7–39-GeV energy range from the beam energy scan program
Olimov K.K. Lebedev I.A. Tukhtaev B.J. Fedosimova A.I. Liu F.-H. Khudoyberdieva S.A. Kanokova S.Z.
1 December 2023World Scientific
International Journal of Modern Physics E
2023#32Issue 12
The hNparti dependencies of the experimental average transverse momentum, hpti, of the charged pions, charged kaons, protons and antiprotons produced at midrapidity (jyj < 0:1) in Au þ Au collisions from the Beam Energy Scan (BES) program at the RHIC (Relativistic Heavy Ion Collider), measured by STAR Collaboration in the ðsnnÞ1=2 ¼ 7–39-GeV energy range, have been described quite well with the power-law model function. We have obtained 0 < αðpionÞ < αðkaonÞ < αððantiÞprotonÞ < 0:2 inequality at all BES energies, indicating the clear mass ordering (dependence) of the power parameter α. On the whole, the exponent parameter α for the charged kaons as well as (anti)protons decreases noticeably with increasing Au þ Au collision energy from ðsnnÞ1=2 ¼ 7:7 GeV to ðsnnÞ1=2 ¼ 39 GeV. Drastic change observed in the energy (snn) dependence of the parameter α for the charged kaons at ðsnnÞ1=2 ≈ 39 GeV could possibly indicate a signi¯cant change in the mechanism(s) of the charged kaon production in Au þ Au collisions at around ðsnnÞ1=2 ≈ 39 GeV. Signi¯cant change in the ðsnnÞ1=2 dependence of the parameter α for the charged pions observed at around ðsnnÞ1=2 ≈ 20 GeV is consistent with a possible change in the mechanism(s) of the particle production in Au þ Au collisions at around ðsnnÞ1=2 ≈ 20 GeV, reported earlier by STAR Collaboration. Signi¯cant gaps between α (protons) and α (antiprotons) as well as between (πþ) and αðπ̄Þ have been seen in the region ðsnnÞ1=2 ¼ 7–20 GeV. These gaps diminish and practically disappear with ðπþÞ ≈ αðπ̄Þ and α (protons) ≈ α (antiprotons) in the region ðsnnÞ1=2 > 20 GeV. Altogether, the ¯ndings, regarding collision energy dependencies of the parameter α for the studied particle species, could indicate the probable phase transition of a nuclear matter to the mixed phase of QGP and hadrons taking place in Au þ Au collisions at around ðsnnÞ1=2 ≈ 20 GeV. The di®erences found between parameter α versus ðsnnÞ1=2 dependencies of the particles and antiparticles have been connected with the ratios of antiparticle and particle yields and di®erences in the mechanisms of production of particles and antiparticles. It is deduced that the exponent parameter α should be sensitive to the degree of particle (system) thermalization and particle production mechanisms, and its drastic change could be related to the change in the mechanisms of particle production or/and phase transitions in the nuclear/hadronic matter. #c World Scienti¯c Publishing Company.
average transverse momentum (hpti) , degree of particle (matter) thermalization , degree of °attening of the hpti versus hNparti spectrum , evolution of midrapidity hpti , Heavy-ion collisions from the BES program at the RHIC , mechanisms of particle production , mixed phase of QGP and hadrons , power-law model function , transverse momentum distributions of particles
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Physical-Technical Institute of Uzbekistan Academy of Sciences, Chingiz Aytmatov Street 2b, Tashkent, 100084, Uzbekistan
Institute of Physics and Technology, Satbayev University, Almaty, Kazakhstan
National University of Science and Technology MISIS (NUST MISIS), Almalyk Branch, Almalyk, Uzbekistan
Institute of Nuclear Physics, Almaty, Kazakhstan
Institute of Theoretical Physics, Shanxi University, Shanxi, Taiyuan, 030006, China
Collaborative Innovation Center of Extreme Optics, Shanxi University, Shanxi, Taiyuan, 030006, China
State Key Laboratory of Quantum Optics and Quantum Optics Devices, Shanxi University, Shanxi, Taiyuan, 030006, China
Physical-Technical Institute of Uzbekistan Academy of Sciences
Institute of Physics and Technology
National University of Science and Technology MISIS (NUST MISIS)
Institute of Nuclear Physics
Institute of Theoretical Physics
Collaborative Innovation Center of Extreme Optics
State Key Laboratory of Quantum Optics and Quantum Optics Devices
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