We report measurements of the nuclear modification factor RCP for charged hadrons as well as identified π+(−), K+(−), and p(p¯) for Au + Au collision energies of √sNN = 7.7, 11.5, 14.5, 19.6, 27, 39, and 62.4 GeV. We observe a clear high-pT net suppression in central collisions at 62.4 GeV for charged hadrons which evolves smoothly to a large net enhancement at lower energies. This trend is driven by the evolution of the pion spectra but is also very similar for the kaon spectra. While the magnitude of the proton RCP at high pT does depend on the collision energy, neither the proton nor the antiproton RCP at high pT exhibit net suppression at any energy. A study of how the binary collision-scaled high-pT yield evolves with centrality reveals a nonmonotonic shape that is consistent with the idea that jet quenching is increasing faster than the combined phenomena that lead to enhancement.
Digital Object Identifier (DOI)
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, the Ministry of Education and Science of the Russian Federation, 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 National Research Foundation of Korea, GA and MSMT of the Czech Republic, Department of Atomic Energy and Department of Science and Technology of the Government of India, the National Science Centre of Poland, National Research Foundation, the Ministry of Science, Education and Sports of the Republic of Croatia, RosAtom of Russia,and German Bundesministerium fur Bildung, Wissenschaft, Forschung and Technologie (BMBF) and the Helmholtz Association.
See Supplemental Material at http://link.aps.org/supplemental/10.1103/PhysRevLett.121.032301 for the pT spectra and centrality determination, which includes Refs. [50,51].
Adamczyk, L.; Adams, J. R.; Adkins, J. Kevin; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Ajitanand, N. N.; Alekseev, I.; Anderson, D. M.; Aoyama, R.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Ashraf, M. U.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Barish, K.; Behera, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcikova, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Fatemi, Renee H.; and Ramachandran, Suvarna, "Beam Energy Dependence of Jet-Quenching Effects in Au + Au Collisions at √sNN = 7.7, 11.5, 14.5, 19.6, 27, 39, and 62.4 GeV" (2018). Physics and Astronomy Faculty Publications. 613.