Measurements of Proton High-Order Cumulants in sNN =3 GeV Au+Au Collisions and Implications for the QCD Critical Point

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30 Scopus citations


We report cumulants of the proton multiplicity distribution from dedicated fixed-target Au+Au collisions at sNN=3.0 GeV, measured by the STAR experiment in the kinematic acceptance of rapidity (y) and transverse momentum (pT) within -0.5<y<0 and 0.4<pT<2.0 GeV/c. In the most central 0%-5% collisions, a proton cumulant ratio is measured to be C4/C2=-0.85±0.09 (stat)±0.82 (syst), which is 2σ below the Poisson baseline with respect to both the statistical and systematic uncertainties. The hadronic transport UrQMD model reproduces our C4/C2 in the measured acceptance. Compared to higher energy results and the transport model calculations, the suppression in C4/C2 is consistent with fluctuations driven by baryon number conservation and indicates an energy regime dominated by hadronic interactions. These data imply that the QCD critical region, if created in heavy-ion collisions, could only exist at energies higher than 3 GeV.

Original languageEnglish
Article number202303
JournalPhysical Review Letters
Issue number20
StatePublished - May 20 2022

Bibliographical note

Funding Information:
We thank Dr. V. Koch, Dr. A. Sorensen, and Dr. V. Vovchenko for interesting discussions. We thank the RHIC Operations Group and RCF at BNL, the NERSC Center at LBNL, and the Open Science Grid consortium for providing resources and support. This work was supported in part by the Office of Nuclear Physics within the U.S. DOE Office of Science, the U.S. National Science Foundation, National Natural Science Foundation of China, Chinese Academy of Science, the Ministry of Science and Technology of China and the Chinese Ministry of Education, the Higher Education Sprout Project by Ministry of Education at NCKU, the National Research Foundation of Korea, Czech Science Foundation and Ministry of Education, Youth and Sports of the Czech Republic, Hungarian National Research, Development and Innovation Office, New National Excellency Programme of the Hungarian Ministry of Human Capacities, Department of Atomic Energy and Department of Science and Technology of the Government of India, the National Science Centre of Poland, the Ministry of Science, Education and Sports of the Republic of Croatia and German Bundesministerium für Bildung, Wissenschaft, Forschung and Technologie (BMBF), Helmholtz Association, Ministry of Education, Culture, Sports, Science, and Technology (MEXT), and Japan Society for the Promotion of Science (JSPS).

Publisher Copyright:
© 2022 American Physical Society.

ASJC Scopus subject areas

  • Physics and Astronomy (all)


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