Observation of Excess J/psi Yield at Very Low Transverse Momenta in Au plus Au Collisions at root S-NN =200 GeV and U+U Collisions at root S-NN =193 GeV
Result description
We report on the first measurements of J/psi production at very low transverse momentum (p(T) < 0.2 GeV/c) in hadronic Au + Au collisions at root S-NN = 200 GeV and U + U collisions at ONN = 193 GeV. Remarkably, the inferred nuclear modification factor of J/psi at midrapidity in Au + Au (U + U) collisions reaches about 24 (52) for p(T) < 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/psi for the very low p(T) 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/psi yield observed at extremely low p(T) originates from coherent photon-nucleus interactions. In particular, coherently produced J/psi in violent hadronic collisions may provide a novel probe of the quark-gluon plasma.
Keywords
The result's identifiers
Result code in IS VaVaI
Alternative codes found
RIV/68407700:21340/19:00334357
Result on the web
DOI - Digital Object Identifier
Alternative languages
Result language
angličtina
Original language name
Observation of Excess J/psi Yield at Very Low Transverse Momenta in Au plus Au Collisions at root S-NN =200 GeV and U+U Collisions at root S-NN =193 GeV
Original language description
We report on the first measurements of J/psi production at very low transverse momentum (p(T) < 0.2 GeV/c) in hadronic Au + Au collisions at root S-NN = 200 GeV and U + U collisions at ONN = 193 GeV. Remarkably, the inferred nuclear modification factor of J/psi at midrapidity in Au + Au (U + U) collisions reaches about 24 (52) for p(T) < 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/psi for the very low p(T) 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/psi yield observed at extremely low p(T) originates from coherent photon-nucleus interactions. In particular, coherently produced J/psi in violent hadronic collisions may provide a novel probe of the quark-gluon plasma.
Czech name
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Czech description
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Classification
Type
Jimp - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10303 - Particles and field physics
Result continuities
Project
Result was created during the realization of more than one project. More information in the Projects tab.
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)
Others
Publication year
2019
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Physical Review Letters
ISSN
0031-9007
e-ISSN
—
Volume of the periodical
123
Issue of the periodical within the volume
13
Country of publishing house
US - UNITED STATES
Number of pages
8
Pages from-to
132302
UT code for WoS article
000488270200018
EID of the result in the Scopus database
2-s2.0-85073061405
Result type
Jimp - Article in a specialist periodical, which is included in the Web of Science database
OECD FORD
Particles and field physics
Year of implementation
2019