@article{10902/34238,
year = {2024},
month = {7},
url = {https://hdl.handle.net/10902/34238},
abstract = {Ultrarelativistic nuclear collisions create a strongly interacting state of hot and dense
quark–gluon matter that exhibits a remarkable collective flow behavior with minimal viscous
dissipation. To gain deeper insights into its intrinsic nature and fundamental degrees of freedom, we determine the speed of sound in an extended volume of quark–gluon plasma using lead–lead (PbPb) collisions at a center-of-mass energy per nucleon pair of 5.02 TeV. The data were recorded by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 0.607 nb−¹. The measurement is performed by studying the multiplicity dependence of the average transverse momentum of charged particles emitted in head-on PbPb collisions. Our findings reveal that the speed of sound in this matter is nearly half the speed of light, with a squared value of 0.241 ± 0.002(stat) ± 0.016(syst) in natural units. The effective medium temperature, estimated using the mean transverse momentum, is 219 ± 8(syst)MeV. The measured squared speed of sound at this temperature aligns precisely with predictions from lattice quantum chromodynamic (QCD) calculations. This result provides a stringent constraint on the equation of state of the created medium and direct evidence for a deconfined QCD phase being attained in relativistic nuclear collisions.},
organization = {Individuals have received support from the MarieCurie program and the European Research Council and Horizon 2020 Grant, Contract Nos. 675440, 724704, 752730, 758316, 765710, 824093, and COST Action CA16108 (European Union); the Leventis Foundation; the Alfred P. Sloan Foundation; the Alexander von Humboldt Foundation; the Science Committee, project no. 22rl-037 (Armenia); the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap
voor Innovatie door Wetenschap en Technologie (IWTBelgium); the F.R.S.-FNRS and FWO (Belgium) under the
‘Excellence of Science—EOS’ – be.h project n. 30820817; the Beijing Municipal Science & Technology Commission, No. Z191100007219010 and Fundamental Research Funds for the Central Universities (China); the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Shota Rustaveli National Science Foundation, grant FR22-985 (Georgia); the Deutsche Forschungsgemeinschaft (DFG), under Germany’s Excellence Strategy—EXC 2121 ‘Quantum Universe’—390833306, and under Project Number 400140256—GRK2497; the Hellenic Foundation for Research and Innovation (HFRI), Project Number 2288 (Greece); the Hungarian Academy of Sciences, the New National Excellence Program—UNKP, the NKFIH research grants K 124845, K 124850, K 128713, K 128786, K 129058, K 131991, K 133046, K 138136, K 143460, K 143477, 2020- 2.2.1-ED-2021-00181, and TKP2021-NKTA-64 (Hungary); the Council of Science and Industrial Research, India; ICSC—National Research Center for High Performance Computing, Big Data and Quantum Computing, funded by the Next GenerationEU program (Italy); the Latvian Council of Science; the Ministry of Education and Science, Project No. 2022/WK/14, and the National Science Center, Contracts Opus 2021/41/B/ST2/01369 and 2021/43/B/ST2/01552 (Poland); the Fundaçao para a Ciência e a Tecnologia, grant CEECIND/01334/2018 (Portugal); the National Priorities Research Program by Qatar National Research Fund; MCIN/AEI/10.13039/501100011033, ERDF ‘a way of making Europe’, and the Programa Estatal de Fomento de la
Investigación Científica y Técnica de Excelencia María de Maeztu, Grant MDM-2017-0765 and Programa Severo
Ochoa del Principado de Asturias (Spain); the Chulalongkorn Academic into Its 2nd Century Project Advancement Project, and the National Science, Research and Innovation Fund via the Program Management Unit for Human Resources & Institutional Development, Research and Innovation, Grant B37G660013 (Thailand); the Kavli Foundation; the Nvidia Corporation; the SuperMicro Corporation; the Welch Foundation, contract C-1845; and the Weston Havens Foundation (USA).},
publisher = {Institute of Physics Publishing},
publisher = {Reports on Progress in Physics, 2024, 87(7), 077801},
title = {Extracting the speed of sound in quark-gluon plasma with ultrarelativistic lead-lead collisions at the LHC},
author = {Hayrapetyan, A. and Bhowmik, Sandeep and Blanco Fernández, Sergio and Brochero Cifuentes, Javier Andrés and Cabrillo Bartolomé, José Ibán and Calderón Tazón, Alicia and Duarte Campderros, Jorge and Fernández García, Marcos and Gómez Gramuglio, Gervasio and Lasaosa García, Clara and Martínez Rivero, Celso and Martínez Ruiz del Árbol, Pablo and Matorras Weinig, Francisco and Matorras Cuevas, Pablo and Navarrete Ramos, Efrén and Piedra Gómez, Jonatan and Scodellaro, Luca and Vila Álvarez, Iván and Vizán García, Jesús Manuel},
}