Centrality dependence of low-momentum direct-photon production in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV

Journal Article

The PHENIX experiment at RHIC has measured the centrality dependence of the direct photon yield from Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV down to $p_T=0.4$ GeV/$c$. Photons are detected via photon conversions to $e^+e^-$ pairs and an improved technique is applied that minimizes the systematic uncertainties that usually limit direct photon measurements, in particular at low $p_T$. We find an excess of direct photons above the $N_{\rm coll}$-scaled yield measured in $p$$+$$p$ collisions. This excess yield is well described by an exponential distribution with an inverse slope of about 240 MeV/$c$ in the $p_T$ range from 0.6--2.0 GeV/$c$. While the shape of the $p_T$ distribution is independent of centrality within the experimental uncertainties, the yield increases rapidly with increasing centrality, scaling approximately with $N_{\rm part}^\alpha$, where $\alpha=1.48{\pm}0.08({\rm stat}){\pm}0.04({\rm syst})$.

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  • Adare, A; Afanasiev, S; Aidala, C; Ajitanand, NN; Akiba, Y; Akimoto, R; Al-Bataineh, H; Al-Ta'ani, H; Alexander, J; Angerami, A; Aoki, K; Apadula, N; Aramaki, Y; Asano, H; Aschenauer, EC; Atomssa, ET; Averbeck, R; Awes, TC; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Bannier, B; Barish, KN; Bassalleck, B; Basye, AT; Bathe, S; Baublis, V; Baumann, C; Baumgart, S; Bazilevsky, A; Belikov, S; Belmont, R; Bennett, R; Berdnikov, A; Berdnikov, Y; Bickley, AA; Bing, X; Blau, DS; Bok, JS; Boyle, K; Brooks, ML; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Camacho, CM; Campbell, S; Castera, P; Chen, C-H; Chi, CY; Chiu, M; Choi, IJ; Choi, JB; Choi, S; Choudhury, RK; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, BA; Connors, M; Constantin, P; Csanád, M; Csörgő, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; Daugherity, MS; David, G; Denisov, A; Deshpande, A; Desmond, EJ; Dharmawardane, KV; Dietzsch, O; Ding, L; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, KA; Durham, JM; Durum, A; Dutta, D; D'Orazio, L; Edwards, S; Efremenko, YV; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Eyser, KO; Fadem, B; Fields, DE; Finger, M; M. Finger, J; Fleuret, F; Fokin, SL; Fraenkel, Z; Frantz, JE; Franz, A; Frawley, AD; Fujiwara, K; Fukao, Y; Fusayasu, T; Gainey, K; Gal, C; Garishvili, A; Garishvili, I; Glenn, A; Gong, H; Gong, X; Gonin, M; Goto, Y; Cassagnac, RGD; Grau, N; Greene, SV; Perdekamp, MG; Gunji, T; Guo, L; Gustafsson, H-Å; Hachiya, T; Haggerty, JS; Hahn, KI; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Hartouni, EP; Hashimoto, K; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, TK; Hester, T; Hill, JC; Hohlmann, M; Hollis, RS; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hori, Y; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Ide, J; Iinuma, H; Ikeda, Y; Imai, K; Imrek, J; Inaba, M; Iordanova, A; Isenhower, D; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Ivanischev, D; Ivanishchev, D; Jacak, BV; Javani, M; Jia, J; Jiang, X; Jin, J; Johnson, BM; Joo, KS; Jouan, D; Jumper, DS; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kaneti, S; Kang, BH; Kang, JH; Kang, JS; Kapustinsky, J; Karatsu, K; Kasai, M; Kawall, D; Kawashima, M; Kazantsev, AV; Kempel, T; Khanzadeev, A; Kijima, KM; Kim, BI; Kim, C; Kim, DH; Kim, DJ; Kim, E; Kim, E-J; Kim, HJ; Kim, K-B; Kim, SH; Kim, Y-J; Kim, YK; Kinney, E; Kiriluk, K; Kiss, Á; Kistenev, E; Klatsky, J; Kleinjan, D; Kline, P; Kochenda, L; Komatsu, Y; Komkov, B; Konno, M; Koster, J; Kotchetkov, D; Kotov, D; Kozlov, A; Král, A; Kravitz, A; Krizek, F; Kunde, GJ; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, GS; Lacey, R; Lai, YS; Lajoie, JG; Lebedev, A; Lee, B; Lee, DM; Lee, J; Lee, K; Lee, KB; Lee, KS; Lee, SH; Lee, SR; Leitch, MJ; Leite, MAL; Leitgab, M; Leitner, E; Lenzi, B; Lewis, B; Li, X; Liebing, P; Lim, SH; Levy, LAL; Liška, T; Litvinenko, A; Liu, H; Liu, MX; Love, B; Luechtenborg, R; Lynch, D; Maguire, CF; Makdisi, YI; Makek, M; Malakhov, A; Malik, MD; Manion, A; Manko, VI; Mannel, E; Mao, Y; Masui, H; Masumoto, S; Matathias, F; McCumber, M; McGaughey, PL; McGlinchey, D; McKinney, C; Means, N; Mendoza, M; Meredith, B; Miake, Y; Mibe, T; Mignerey, AC; Mikeš, P; Miki, K; Milov, A; Mishra, DK; Mishra, M; Mitchell, JT; Miyachi, Y; Miyasaka, S; Mohanty, AK; Moon, HJ; Morino, Y; Morreale, A; Morrison, DP; Motschwiller, S; Moukhanova, TV; Murakami, T; Murata, J; Nagae, T; Nagamiya, S; Nagle, JL; Naglis, M; Nagy, MI; Nakagawa, I; Nakamiya, Y; Nakamura, KR; Nakamura, T; Nakano, K; Nattrass, C; Nederlof, A; Newby, J; Nguyen, M; Nihashi, M; Nouicer, R; Novitzky, N; Nyanin, AS; O'Brien, E; Oda, SX; Ogilvie, CA; Oka, M; Okada, K; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, BH; Park, IH; Park, J; Park, SK; Park, WJ; Pate, SF; Patel, L; Pei, H; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, DY; Petti, R; Pinkenburg, C; Pisani, RP; Proissl, M; Purschke, ML; Purwar, AK; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, KF; Reygers, K; Reynolds, D; Riabov, V; Riabov, Y; Richardson, E; Riveli, N; Roach, D; Roche, G; Rolnick, SD; Rosati, M; Rosen, CA; Rosendahl, SSE; Rosnet, P; Rukoyatkin, P; Ružička, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Samsonov, V; Sano, M; Sano, S; Sarsour, M; Sato, T; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Semenov, AY; Sen, A; Seto, R; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, CL; Silvermyr, D; Silvestre, C; Sim, KS; Singh, BK; Singh, CP; Singh, V; Slunečka, M; Soltz, RA; Sondheim, WE; Sorensen, SP; Soumya, M; Sourikova, IV; Sparks, NA; Stankus, PW; Stenlund, E; Stepanov, M; Ster, A; Stoll, SP; Sugitate, T; Sukhanov, A; Sun, J; Sziklai, J; Takagui, EM; Takahara, A; Taketani, A; Tanabe, R; Tanaka, Y; Taneja, S; Tanida, K; Tannenbaum, MJ; Tarafdar, S; Taranenko, A; Tarján, P; Tennant, E; Themann, H; Thomas, TL; Todoroki, T; Togawa, M; Toia, A; Tomášek, L; Tomášek, M; Torii, H; Towell, RS; Tserruya, I; Tsuchimoto, Y; Tsuji, T; Vale, C; Valle, H; Hecke, HWV; Vargyas, M; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Vinogradov, AA; Virius, M; Vossen, A; Vrba, V; Vznuzdaev, E; Wang, XR; Watanabe, D; Watanabe, K; Watanabe, Y; Watanabe, YS; Wei, F; Wei, R; Wessels, J; Whitaker, S; White, SN; Winter, D; Wolin, S; Wood, JP; Woody, CL; Wright, RM; Wysocki, M; Xie, W; Yamaguchi, YL; Yamaura, K; Yang, R; Yanovich, A; Ying, J; Yokkaichi, S; You, Z; Young, GR; Younus, I; Yushmanov, IE; Zajc, WA; Zelenski, A; Zhang, C; Zhou, S; Zolin, L