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arXiv · 1312.3675

Suppression of Upsilon Production in d+Au and Au+Au Collisions at sqrt(s_NN) = 200 GeV

L. Adamczyk·J. K. Adkins·G. Agakishiev·M. M. Aggarwal·Z. Ahammed·I. Alekseev·J. Alford·C. D. Anson·A. Aparin·D. Arkhipkin·E. C. Aschenauer·G. S. Averichev·A. Banerjee·D. R. Beavis·R. Bellwied·A. Bhasin·A. K. Bhati·P. Bhattarai·H. Bichsel·J. Bielcik·J. Bielcikova·L. C. Bland·I. G. Bordyuzhin·W. Borowski·J. Bouchet·A. V. Brandin·S. G. Brovko·S. Bültmann·I. Bunzarov·T. P. Burton·J. Butterworth·H. Caines·M. Calderón de la Barca Sánchez·D. Cebra·R. Cendejas·M. C. Cervantes·P. Chaloupka·Z. Chang·S. Chattopadhyay·H. F. Chen·J. H. Chen·L. Chen·J. Cheng·M. Cherney·A. Chikanian·W. Christie·J. Chwastowski·M. J. M. Codrington·G. Contin·J. G. Cramer·H. J. Crawford·X. Cui·S. Das·A. Davila Leyva·L. C. De Silva·R. R. Debbe·T. G. Dedovich·J. Deng·A. A. Derevschikov·R. Derradi de Souza·S. Dhamija·B. di Ruzza·L. Didenko·C. Dilks·F. Ding·P. Djawotho·X. Dong·J. L. Drachenberg·J. E. Draper·C. M. Du·L. E. Dunkelberger·J. C. Dunlop·L. G. Efimov·J. Engelage·K. S. Engle·G. Eppley·L. Eun·O. Evdokimov·R. Fatemi·S. Fazio·J. Fedorisin·P. Filip·E. Finch·Y. Fisyak·C. E. Flores·C. A. Gagliardi·D. R. Gangadharan·D. Garand·F. Geurts·A. Gibson·M. Girard·S. Gliske·L. Greiner·D. Grosnick·Y. Guo·A. Gupta·S. Gupta·W. Guryn·B. Haag·O. Hajkova
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Abstract

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 (sys.) +/- 0.10 (pp sys.). A comparison with models including shadowing and initial state parton 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 (sys.) +/- 0.06 (pp sys.), 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 additional 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.

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L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev, A. Banerjee, D. R. Beavis, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, H. Bichsel, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, W. Borowski, J. Bouchet, A. V. Brandin, S. G. Brovko, S. Bültmann, I. Bunzarov, T. P. Burton, J. Butterworth, H. Caines, M. Calderón de la Barca Sánchez, D. Cebra, R. Cendejas, M. C. Cervantes, P. Chaloupka, Z. Chang, S. Chattopadhyay, H. F. Chen, J. H. Chen, L. Chen, J. Cheng, M. Cherney, A. Chikanian, W. Christie, J. Chwastowski, M. J. M. Codrington, G. Contin, J. G. Cramer, H. J. Crawford, X. Cui, S. Das, A. Davila Leyva, L. C. De Silva, R. R. Debbe, T. G. Dedovich, J. Deng, A. A. Derevschikov, R. Derradi de Souza, S. Dhamija, B. di Ruzza, L. Didenko, C. Dilks, F. Ding, P. Djawotho, X. Dong, J. L. Drachenberg, J. E. Draper, C. M. Du, L. E. Dunkelberger, J. C. Dunlop, L. G. Efimov, J. Engelage, K. S. Engle, G. Eppley, L. Eun, O. Evdokimov, R. Fatemi, S. Fazio, J. Fedorisin, P. Filip, E. Finch, Y. Fisyak, C. E. Flores, C. A. Gagliardi, D. R. Gangadharan, D. Garand, F. Geurts, A. Gibson, M. Girard, S. Gliske, L. Greiner, D. Grosnick, Y. Guo, A. Gupta, S. Gupta, W. Guryn, B. Haag, O. Hajkova. 2015-01-21. Suppression of Upsilon Production in d+Au and Au+Au Collisions at sqrt(s_NN) = 200 GeV. https://doi.org/10.1016/j.physletb.2014.06.028

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