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

0509904 - ÚJF 2020 RIV US eng J - Journal Article
Adam, J. - Adamczyk, L. - Adams, J. R. - Adkins, J. K. - Agakishiev, G. - Bielčík, J. - Bielčíková, Jana - Federič, Pavol - Chaloupka, P. - Holub, L. - Kocan, M. - Kosarzewski, L. K. - Kramárik, L. - Líčeník, R. - Matonoha, O. - Moravcová, Z. - Rusňák, Jan - Rusňáková, O. - Šimko, Miroslav - Šumbera, Michal - Vaněk, Jan … Total 335 authors
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.
Physical Review Letters. Roč. 123, č. 13 (2019), č. článku 132302. ISSN 0031-9007. E-ISSN 1079-7114
R&D Projects: GA MŠMT LTT18002
Institutional support: RVO:61389005
Keywords : STAR collaboration * heavy ion collisions
OECD category: Particles and field physics
Impact factor: 8.385, year: 2019
Method of publishing: Open access
https://doi.org/10.1103/PhysRevLett.123.132302

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.
Permanent Link: http://hdl.handle.net/11104/0300544