Abstract
The PHENIX experiment measured the centrality dependence of two-pion Bose-Einstein correlation functions in sNN=200GeV Au+Au collisions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. The data are well represented by Lévy-stable source distributions. The extracted source parameters are the correlation-strength parameter λ, the Lévy index of stability α, and the Lévy-scale parameter R as a function of transverse mass mT and centrality. The λ(mT) parameter is constant at larger values of mT, but decreases as mT decreases. The Lévy-scale parameter R(mT) decreases with mT and exhibits proportionality to the length scale of the nuclear overlap region. The Lévy exponent α(mT) is independent of mT within uncertainties in each investigated centrality bin, but shows a clear centrality dependence. At all centralities, the Lévy exponent α is significantly different from that of Gaussian (α=2) or Cauchy (α=1) source distributions. Comparisons to the predictions of Monte-Carlo simulations of resonance-decay chains show that, in all but the most peripheral centrality class (50%-60%), the obtained results are inconsistent with the measurements, unless a significant reduction of the in-medium mass of the η′ meson is included. In each centrality class, the best value of the in-medium η′ mass is compared to the mass of the η meson, as well as to several theoretical predictions that consider restoration of UA(1) symmetry in hot hadronic matter.
| Original language | English |
|---|---|
| Article number | 064909 |
| Journal | Physical Review C |
| Volume | 110 |
| Issue number | 6 |
| DOIs | |
| State | Published - Dec 2024 |
Funding
We thank the staff of the Collider-Accelerator and Physics Departments at Brookhaven National Laboratory and the staff of the other PHENIX participating institutions for their vital contributions. We acknowledge clarifying and inspiring discussions with S\u00E1ndor Hegyi, Dubravko Klabu\u010Dar, Robert Pisarski, and Gy\u00F6rgy Wolf concerning the interpretation of their published results. S.L. thanks IFJ PAN, Krakow, Poland for their encouragement to finish this work. We acknowledge support from the Office of Nuclear Physics in the Office of Science of the Department of Energy, the National Science Foundation, Abilene Christian University Research Council, Research Foundation of SUNY, and Dean of the College of Arts and Sciences, Vanderbilt University (USA); Ministry of Education, Culture, Sports, Science, and Technology, and the Japan Society for the Promotion of Science (Japan), Conselho Nacional de Desenvolvimento Cient\u00EDfico e Tecnol\u00F3gico and Funda\u00E7\u00E3o de Amparo \u00E0 Pesquisa do Estado de S\u00E3o Paulo (Brazil); Natural Science Foundation of China (People's Republic of China); Croatian Science Foundation and Ministry of Science and Education (Croatia); Ministry of Education, Youth and Sports (Czech Republic); Centre National de la Recherche Scientifique, Commissariat \u00E0 l'\u00C9nergie Atomique, and Institut National de Physique Nucl\u00E9aire et de Physique des Particules (France); J. Bolyai Research Scholarship, EFOP, HUN-REN ATOMKI, NKFIH, MATE KKP, and OTKA (Hungary); Department of Atomic Energy and Department of Science and Technology (India); Israel Science Foundation (Israel); Basic Science Research and SRC(CENuM) Programs through NRF funded by the Ministry of Education and the Ministry of Science and ICT (Korea); Ministry of Education and Science, Russian Academy of Sciences, Federal Agency of Atomic Energy (Russia); VR and Wallenberg Foundation (Sweden); University of Zambia, the Government of the Republic of Zambia (Zambia); the U.S. Civilian Research and Development Foundation for the Independent States of the Former Soviet Union, the Hungarian American Enterprise Scholarship Fund, the US-Hungarian Fulbright Foundation, and the US-Israel Binational Science Foundation.