Observation of Excess J /ψ Yield at Very Low Transverse Momenta in Au+Au Collisions at sNN =200 GeV and U+ U Collisions at sNN =193 GeV

doi:10.1103/PhysRevLett.123.132302

Observation of Excess J /ψ Yield at Very Low Transverse Momenta in Au+Au Collisions at sNN =200 GeV and U+ U Collisions at sNN =193 GeV

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Abstract

We report on the first measurements of J/ψ production at very low transverse momentum (pT<0.2 GeV/c) in hadronic Au+Au collisions at sNN=200 GeV and U+U collisions at sNN=193 GeV. Remarkably, the inferred nuclear modification factor of J/ψ at midrapidity in Au+Au (U+U) collisions reaches about 24 (52) for pT<0.05 GeV/c in the 60%-80% collision centrality class. This noteworthy enhancement cannot be explained by hadronic production accompanied by cold and hot medium effects. In addition, the dN/dt distribution of J/ψ for the very low pT range is presented for the first time. The distribution is consistent with that expected from the Au nucleus and shows a hint of interference. Comparison of the measurements to theoretical calculations of coherent production shows that the excess yield can be described reasonably well and reveals a partial disruption of coherent production in semicentral collisions, perhaps due to the violent hadronic interactions. Incorporating theoretical calculations, the results strongly suggest that the dramatic enhancement of J/ψ yield observed at extremely low pT originates from coherent photon-nucleus interactions. In particular, coherently produced J/ψ's in violent hadronic collisions may provide a novel probe of the quark-gluon plasma.

Original language	English
Article number	132302
Journal	Physical Review Letters
Volume	123
Issue number	13
DOIs	https://doi.org/10.1103/PhysRevLett.123.132302
State	Published - Sep 27 2019

Bibliographical note

Publisher Copyright:
© 2019 authors. Published by the American Physical Society.

Funding

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, 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, Czech Science Foundation and Ministry of Education, Youth and Sports 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, 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.

Funders	Funder number
RosAtom of Russia and German Bundesministerium fur Bildung, Wissenschaft, Forschung and Technologie
U.S. Department of Energy Chinese Academy of Sciences Guangzhou Municipal Science and Technology Project Oak Ridge National Laboratory Extreme Science and Engineering Discovery Environment National Science Foundation National Energy Research Scientific Computing Center National Natural Science Foundation of China
National Science Foundation Office of International Science and Engineering
Horia Hulubei National Institute for Physics and Nuclear Engineering
Department of Science and Technology, Ministry of Science and Technology, India
Japan Society for the Promotion of Science Fund for the Promotion of Joint International Research	19H05598
Japan Society for the Promotion of Science Fund for the Promotion of Joint International Research
National Natural Science Foundation of China (NSFC)
Ministerstvo Školství, Mládeže a Tělovýchovy
Grantová Agentura České Republiky
Ministry of Education of the People's Republic of China
Bundesministerium für Bildung und Forschung
Chinese Academy of Sciences
Ministry of Science and Technology of the People's Republic of China
Ministarstvo Obrazovanja, Znanosti i Sporta
Ministry for Education and Science of the Russian Federation
National Research Foundation of Korea
Narodowe Centrum Nauki
Max Delbrück Center for Molecular Medicine in the Helmholtz Association

ASJC Scopus subject areas

General Physics and Astronomy

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10.1103/PhysRevLett.123.132302

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@article{4c432494f7724e3e9da7dd7a6d979956,

title = "Observation of Excess J /ψ Yield at Very Low Transverse Momenta in Au+Au Collisions at sNN =200 GeV and U+ U Collisions at sNN =193 GeV",

abstract = "We report on the first measurements of J/ψ production at very low transverse momentum (pT<0.2 GeV/c) in hadronic Au+Au collisions at sNN=200 GeV and U+U collisions at sNN=193 GeV. Remarkably, the inferred nuclear modification factor of J/ψ at midrapidity in Au+Au (U+U) collisions reaches about 24 (52) for pT<0.05 GeV/c in the 60\%-80\% collision centrality class. This noteworthy enhancement cannot be explained by hadronic production accompanied by cold and hot medium effects. In addition, the dN/dt distribution of J/ψ for the very low pT range is presented for the first time. The distribution is consistent with that expected from the Au nucleus and shows a hint of interference. Comparison of the measurements to theoretical calculations of coherent production shows that the excess yield can be described reasonably well and reveals a partial disruption of coherent production in semicentral collisions, perhaps due to the violent hadronic interactions. Incorporating theoretical calculations, the results strongly suggest that the dramatic enhancement of J/ψ yield observed at extremely low pT originates from coherent photon-nucleus interactions. In particular, coherently produced J/ψ's in violent hadronic collisions may provide a novel probe of the quark-gluon plasma.",

author = "J. Adam and L. Adamczyk and Adams, \{J. R.\} and Adkins, \{J. K.\} and G. Agakishiev and Aggarwal, \{M. M.\} and Z. Ahammed and I. Alekseev and Anderson, \{D. M.\} and R. Aoyama and A. Aparin and D. Arkhipkin and Aschenauer, \{E. C.\} and Ashraf, \{M. U.\} and F. Atetalla and A. Attri and Averichev, \{G. S.\} and V. Bairathi and K. Barish and Bassill, \{A. J.\} and A. Behera and R. Bellwied and A. Bhasin and Bhati, \{A. K.\} and J. Bielcik and J. Bielcikova and Bland, \{L. C.\} and Bordyuzhin, \{I. G.\} and Brandenburg, \{J. D.\} and Brandin, \{A. V.\} and J. Bryslawskyj and I. Bunzarov and J. Butterworth and H. Caines and S{\'a}nchez, \{M. Calder{\'o}n De La Barca\} and D. Cebra and I. Chakaberia and P. Chaloupka and Chan, \{B. K.\} and Chang, \{F. H.\} and Z. Chang and N. Chankova-Bunzarova and A. Chatterjee and S. Chattopadhyay and Chen, \{J. H.\} and X. Chen and J. Cheng and M. Cherney and W. Christie and R. Fatemi",

note = "Publisher Copyright: {\textcopyright} 2019 authors. Published by the American Physical Society.",

year = "2019",

month = sep,

day = "27",

doi = "10.1103/PhysRevLett.123.132302",

language = "English",

volume = "123",

number = "13",

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T1 - Observation of Excess J /ψ Yield at Very Low Transverse Momenta in Au+Au Collisions at sNN =200 GeV and U+ U Collisions at sNN =193 GeV

AU - Adam, J.

AU - Adamczyk, L.

AU - Adams, J. R.

AU - Adkins, J. K.

AU - Agakishiev, G.

AU - Aggarwal, M. M.

AU - Ahammed, Z.

AU - Alekseev, I.

AU - Anderson, D. M.

AU - Aoyama, R.

AU - Aparin, A.

AU - Arkhipkin, D.

AU - Aschenauer, E. C.

AU - Ashraf, M. U.

AU - Atetalla, F.

AU - Attri, A.

AU - Averichev, G. S.

AU - Bairathi, V.

AU - Barish, K.

AU - Bassill, A. J.

AU - Behera, A.

AU - Bellwied, R.

AU - Bhasin, A.

AU - Bhati, A. K.

AU - Bielcik, J.

AU - Bielcikova, J.

AU - Bland, L. C.

AU - Bordyuzhin, I. G.

AU - Brandenburg, J. D.

AU - Brandin, A. V.

AU - Bryslawskyj, J.

AU - Bunzarov, I.

AU - Butterworth, J.

AU - Caines, H.

AU - Sánchez, M. Calderón De La Barca

AU - Cebra, D.

AU - Chakaberia, I.

AU - Chaloupka, P.

AU - Chan, B. K.

AU - Chang, F. H.

AU - Chang, Z.

AU - Chankova-Bunzarova, N.

AU - Chatterjee, A.

AU - Chattopadhyay, S.

AU - Chen, J. H.

AU - Chen, X.

AU - Cheng, J.

AU - Cherney, M.

AU - Christie, W.

AU - Fatemi, R.

PY - 2019/9/27

Y1 - 2019/9/27

N2 - We report on the first measurements of J/ψ production at very low transverse momentum (pT<0.2 GeV/c) in hadronic Au+Au collisions at sNN=200 GeV and U+U collisions at sNN=193 GeV. Remarkably, the inferred nuclear modification factor of J/ψ at midrapidity in Au+Au (U+U) collisions reaches about 24 (52) for pT<0.05 GeV/c in the 60%-80% collision centrality class. This noteworthy enhancement cannot be explained by hadronic production accompanied by cold and hot medium effects. In addition, the dN/dt distribution of J/ψ for the very low pT range is presented for the first time. The distribution is consistent with that expected from the Au nucleus and shows a hint of interference. Comparison of the measurements to theoretical calculations of coherent production shows that the excess yield can be described reasonably well and reveals a partial disruption of coherent production in semicentral collisions, perhaps due to the violent hadronic interactions. Incorporating theoretical calculations, the results strongly suggest that the dramatic enhancement of J/ψ yield observed at extremely low pT originates from coherent photon-nucleus interactions. In particular, coherently produced J/ψ's in violent hadronic collisions may provide a novel probe of the quark-gluon plasma.

AB - We report on the first measurements of J/ψ production at very low transverse momentum (pT<0.2 GeV/c) in hadronic Au+Au collisions at sNN=200 GeV and U+U collisions at sNN=193 GeV. Remarkably, the inferred nuclear modification factor of J/ψ at midrapidity in Au+Au (U+U) collisions reaches about 24 (52) for pT<0.05 GeV/c in the 60%-80% collision centrality class. This noteworthy enhancement cannot be explained by hadronic production accompanied by cold and hot medium effects. In addition, the dN/dt distribution of J/ψ for the very low pT range is presented for the first time. The distribution is consistent with that expected from the Au nucleus and shows a hint of interference. Comparison of the measurements to theoretical calculations of coherent production shows that the excess yield can be described reasonably well and reveals a partial disruption of coherent production in semicentral collisions, perhaps due to the violent hadronic interactions. Incorporating theoretical calculations, the results strongly suggest that the dramatic enhancement of J/ψ yield observed at extremely low pT originates from coherent photon-nucleus interactions. In particular, coherently produced J/ψ's in violent hadronic collisions may provide a novel probe of the quark-gluon plasma.

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DO - 10.1103/PhysRevLett.123.132302

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SN - 0031-9007

VL - 123

JO - Physical Review Letters

JF - Physical Review Letters

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Observation of Excess J /ψ Yield at Very Low Transverse Momenta in Au+Au Collisions at sNN =200 GeV and U+ U Collisions at sNN =193 GeV

Abstract

Bibliographical note

Funding

ASJC Scopus subject areas

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