Evolution of π0 suppression in Au+Au collisions from √s NN=39 to 200 GeV

A. Adare, S. Afanasiev, C. Aidala, N. N. Ajitanand, Y. Akiba, R. Akimoto, H. Al-Ta'Ani, J. Alexander, A. Angerami, K. Aoki, N. Apadula, Y. Aramaki, H. Asano, E. C. Aschenauer, E. T. Atomssa, T. C. Awes, B. Azmoun, V. Babintsev, M. Bai, B. BannierK. N. Barish, B. Bassalleck, S. Bathe, V. Baublis, S. Baumgart, A. Bazilevsky, R. Belmont, A. Berdnikov, Y. Berdnikov, X. Bing, D. S. Blau, K. Boyle, M. L. Brooks, H. Buesching, V. Bumazhnov, S. Butsyk, S. Campbell, P. Castera, C. H. Chen, C. Y. Chi, M. Chiu, I. J. Choi, J. B. Choi, S. Choi, R. K. Choudhury, P. Christiansen, T. Chujo, O. Chvala, V. Cianciolo, Z. Citron, B. A. Cole, M. Connors, M. Csanád, T. Csörgo, S. Dairaku, A. Datta, M. S. Daugherity, G. David, A. Denisov, A. Deshpande, E. J. Desmond, K. V. Dharmawardane, O. Dietzsch, L. Ding, A. Dion, M. Donadelli, O. Drapier, A. Drees, K. A. Drees, J. M. Durham, A. Durum, L. D'Orazio, S. Edwards, Y. V. Efremenko, T. Engelmore, A. Enokizono, S. Esumi, K. O. Eyser, B. Fadem, D. E. Fields, M. Finger, M. Finger, F. Fleuret, S. L. Fokin, J. E. Frantz, A. Franz, A. D. Frawley, Y. Fukao, T. Fusayasu, K. Gainey, C. Gal, A. Garishvili, I. Garishvili, A. Glenn, X. Gong, M. Gonin, Y. Goto, R. Granier De Cassagnac, N. Grau, S. V. Greene, M. Grosse Perdekamp, T. Gunji, L. Guo, H. A. Gustafsson, T. Hachiya, J. S. Haggerty, K. I. Hahn, H. Hamagaki, J. Hanks, K. Hashimoto, E. Haslum, R. Hayano, X. He, T. K. Hemmick, T. Hester, J. C. Hill, R. S. Hollis, K. Homma, B. Hong, T. Horaguchi, Y. Hori, S. Huang, T. Ichihara, H. Iinuma, Y. Ikeda, J. Imrek, M. Inaba, A. Iordanova, D. Isenhower, M. Issah, A. Isupov, D. Ivanischev, B. V. Jacak, M. Javani, J. Jia, X. Jiang, B. M. Johnson, K. S. Joo, D. Jouan, J. Kamin, S. Kaneti, B. H. Kang, J. H. Kang, J. S. Kang, J. Kapustinsky, K. Karatsu, M. Kasai, D. Kawall, A. V. Kazantsev, T. Kempel, A. Khanzadeev, K. M. Kijima, B. I. Kim, C. Kim, D. J. Kim, E. J. Kim, H. J. Kim, K. B. Kim, Y. J. Kim, Y. K. Kim, E. Kinney, A. Kiss, E. Kistenev, J. Klatsky, D. Kleinjan, P. Kline, Y. Komatsu, B. Komkov, J. Koster, D. Kotchetkov, D. Kotov, A. Král, F. Krizek, G. J. Kunde, K. Kurita, M. Kurosawa, Y. Kwon, G. S. Kyle, R. Lacey, Y. S. Lai, J. G. Lajoie, A. Lebedev, B. Lee, D. M. Lee, J. Lee, K. B. Lee, K. S. Lee, S. H. Lee, S. R. Lee, M. J. Leitch, M. A.L. Leite, M. Leitgab, B. Lewis, S. H. Lim, L. A. Linden Levy, A. Litvinenko, M. X. Liu, B. Love, C. F. Maguire, Y. I. Makdisi, M. Makek, A. Malakhov, A. Manion, V. I. Manko, E. Mannel, S. Masumoto, M. McCumber, P. L. McGaughey, D. McGlinchey, C. McKinney, M. Mendoza, B. Meredith, Y. Miake, T. Mibe, A. C. Mignerey, A. Milov, D. K. Mishra, J. T. Mitchell, Y. Miyachi, S. Miyasaka, A. K. Mohanty, H. J. Moon, D. P. Morrison, S. Motschwiller, T. V. Moukhanova, T. Murakami, J. Murata, T. Nagae, S. Nagamiya, J. L. Nagle, M. I. Nagy, I. Nakagawa, Y. Nakamiya, K. R. Nakamura, T. Nakamura, K. Nakano, C. Nattrass, A. Nederlof, M. Nihashi, R. Nouicer, N. Novitzky, A. S. Nyanin, E. O'Brien, C. A. Ogilvie, K. Okada, A. Oskarsson, M. Ouchida, K. Ozawa, R. Pak, V. Pantuev, V. Papavassiliou, B. H. Park, I. H. Park, S. K. Park, S. F. Pate, L. Patel, H. Pei, J. C. Peng, H. Pereira, V. Peresedov, D. Yu Peressounko, R. Petti, C. Pinkenburg, R. P. Pisani, M. Proissl, M. L. Purschke, H. Qu, J. Rak, I. Ravinovich, K. F. Read, R. Reynolds, V. Riabov, Y. Riabov, E. Richardson, D. Roach, G. Roche, S. D. Rolnick, M. Rosati, P. Rukoyatkin, B. Sahlmueller, N. Saito, T. Sakaguchi, V. Samsonov, M. Sano, M. Sarsour, S. Sawada, K. Sedgwick, R. Seidl, A. Sen, R. Seto, D. Sharma, I. Shein, T. A. Shibata, K. Shigaki, M. Shimomura, K. Shoji, P. Shukla, A. Sickles, C. L. Silva, D. Silvermyr, K. S. Sim, B. K. Singh, C. P. Singh, V. Singh, M. Slunečka, R. A. Soltz, W. E. Sondheim, S. P. Sorensen, M. Soumya, I. V. Sourikova, P. W. Stankus, E. Stenlund, M. Stepanov, A. Ster, S. P. Stoll, T. Sugitate, A. Sukhanov, J. Sun, J. Sziklai, E. M. Takagui, A. Takahara, A. Taketani, Y. Tanaka, S. Taneja, K. Tanida, M. J. Tannenbaum, S. Tarafdar, A. Taranenko, E. Tennant, H. Themann, T. Todoroki, L. Tomáek, M. Tomáek, H. Torii, R. S. Towell, I. Tserruya, Y. Tsuchimoto, T. Tsuji, C. Vale, H. W. Van Hecke, M. Vargyas, E. Vazquez-Zambrano, A. Veicht, J. Velkovska, R. Vértesi, M. Virius, A. Vossen, V. Vrba, E. Vznuzdaev, X. R. Wang, D. Watanabe, K. Watanabe, Y. Watanabe, Y. S. Watanabe, F. Wei, R. Wei, S. N. White, D. Winter, S. Wolin, C. L. Woody, M. Wysocki, Y. L. Yamaguchi, R. Yang, A. Yanovich, J. Ying, S. Yokkaichi, Z. You, I. Younus, I. E. Yushmanov, W. A. Zajc, A. Zelenski, L. Zolin

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52 Citations (Scopus)

Abstract

Neutral-pion π0 spectra were measured at midrapidity (|y|<0.35) in Au+Au collisions at √sNN=39 and 62.4GeV and compared with earlier measurements at 200GeV in a transverse-momentum range of 1<p T<10GeV/c. The high-pT tail is well described by a power law in all cases, and the powers decrease significantly with decreasing center-of-mass energy. The change of powers is very similar to that observed in the corresponding spectra for p+p collisions. The nuclear modification factors (RAA) show significant suppression, with a distinct energy, centrality, and pT dependence. Above pT=7GeV/c, R AA is similar for √sNN=62.4 and 200GeV at all centralities. Perturbative-quantum-chromodynamics calculations that describe RAA well at 200GeV fail to describe the 39GeV data, raising the possibility that, for the same pT region, the relative importance of initial-state effects and soft processes increases at lower energies. The p T range where π0 spectra in central Au+Au collisions have the same power as in p+p collisions is 5 and 7GeV/c for √sNN=200 and 62.4GeV, respectively. For the √sNN=39GeV data, it is not clear whether such a region is reached, and the xT dependence of the xT-scaling power-law exponent is very different from that observed in the √sNN=62 and 200GeV data, providing further evidence that initial-state effects and soft processes mask the in-medium suppression of hard-scattered partons to higher pT as the collision energy decreases.

Original languageEnglish
Article number152301
JournalPhysical review letters
Volume109
Issue number15
DOIs
Publication statusPublished - 2012 Oct 9

ASJC Scopus subject areas

  • General Physics and Astronomy

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