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Title: Suppression of Υ production in d + Au + and Au + Au collisions at √ sNN =200 GeV

We report measurements of Upsilon meson production in p + p, d +Au, and Au+Au collisions using the STAR detector at RHIC. We compare the Upsilon yield to the measured cross section in p + p collisions in order to quantify any modifications of the yield in cold nuclear matter using d +Au data and in hot nuclear matter using Au+Au data separated into three centrality classes. Our p +p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for Upsilon (1S + 2S + 3S) in the rapidity range |y| < 1 in d + Au collisions of R dAu = 0.79 ± 0.24(stat.) ± 0.03(syst.) ± 0.10(p + p syst.). A comparison with models including shadowing and initial state part on energy loss indicates the presence of additional cold-nuclear matter suppression. Similarly, in the top 10% most-central Au + Au collisions, we measure a nuclear modification factor of R AA = 0.49 ±0.1(stat.) ±0.02(syst.) ±0.06(p + p syst.), which is a larger suppression factor than that seen in cold nuclear matter. Our results are consistent with complete suppression of excited-state Upsilon mesons in Au + Au collisions. The additionalmore » suppression in Au + Au is consistent with the level expected in model calculations that include the presence of a hot, deconfined Quark–Gluon Plasma. However, understanding the suppression seen in d + Au is still needed before any definitive statements about the nature of the suppression in Au + Au can be made.« less
Publication Date:
Report Number(s):
Journal ID: ISSN 0370-2693; R&D Project: PO 004; KB0202012
Grant/Contract Number:
NRF-2012004024; SC0012704; AC02-06CH11357; AC02-05CH11231
Published Article
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 735; Journal Issue: C; Journal ID: ISSN 0370-2693
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States); Argonne National Lab. (ANL), Argonne, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
STAR Collaboration
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1159733; OSTI ID: 1222222