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
J. Adam , Daniel Kikoła , Adam Kisiel , Andrzej Lipiec , Jan Pluta , Sebastian Siejka , P. Szymanski , Hanna Zbroszczyk
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.
|Collective author||L. Adamczyk, J.R. Adams, J.K. Adkins, G. Agakishiev, M.M. Aggarwal, Z. Ahammed, I. Aleksee.....|
|Journal series||Physical Review Letters, ISSN 0031-9007, e-ISSN 1079-7114, (N/A 200 pkt)|
|Publication size in sheets||0.3|
|Score||= 200.0, 09-01-2020, ArticleFromJournal|
|Publication indicators||= 0; = 0; : 2017 = 2.464; : 2018 = 9.227 (2) - 2018=8.313 (5)|
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.