Low- pT direct-photon production in Au+Au collisions at sNN=39 and 62.4 GeV

N J Abdulameer,L Bichon,S R Lee,M Alfred,I E Yushmanov,D Larionova,E Vazquez-Zambrano,A Kingan,H Torii,M Harvey,I Garishvili,S P Stoll,P V Radzevich,A Manion,H J Kim,D S Jumper,D K Mishra,H Themann,R Seto,L Zou,A Franz,D Firak,T Kempel,Y K Kim,D Kleinjan,K S Sim,R Corliss,X Gong,N Saito,R Pak,D E Fields,E Stenlund,I Younus,M Nihashi,H Hamagaki,K Sedgwick,Y Akiba,K Nakano,C L Silva,T Kim,V Khachatryan,B Lewis,K Watanabe,A Nederlof,T Gunji,S Bathe,B H Park,E Vznuzdaev,M Chiu,Y V Efremenko,T Sakaguchi,I V Sourikova,S D Rolnick,A Hodges,C P Singh,A Dion,N N Ajitanand,R S Hollis,C A Ogilvie,C Kim,X Jiang,L Tomášek,S Nelson,U Acharya,A Sukhanov,V Riabov,J Kamin,S Park,J Hanks,A Mwai,A D Frawley,A Muhammad,R Yang,S Sawada,A Angerami,K.-B Kim,M Issah,E Kinney,A Denisov,S Tarafdar,R Belmont,A Berdnikov,D Winter,V Papavassiliou,S Wolin,I Nakagawa,J E Frantz,T Engelmore,J Ying,M X Liu,M Slunečka,C E Perezlara,G Nukazuka,Y Tsuchimoto,V Pantuev,A Takahara,N Ramasubramanian,M Javani,R P Pisani,B Blankenship,M L Brooks,S Campbell,A Garishvili,K Gainey,N A Lewis,M Patel,J S Kang,M Shimomura,E Mannel,D A Loomis,P W Stankus,J Oh,E J Desmond,V Baublis,M J Leitch,J Koster,F Wei,P L Mcgaughey,B Xia,H Qu,H J Moon,J Velkovska,R A Soltz,D Kincses,T Mibe,E C Aschenauer,K S Joo,Z Shi,H Iinuma,F Fleuret,J Sun,A Vossen,R Esha,Á Kiss,D M Lee,B Kurgyis,D Roach,K B Lee,A Veicht,Y Nakamiya,J D Osborn,A Khatiwada,M Mccumber,W Fan,A Bazilevsky,T Moon,C T Dean,J S Haggerty,K Homma,V Vrba,A Sen,K I Hahn,S Taneja,T V Moukhanova,V Doomra,G S Kyle,P Kline,T Majoros,A Milov,A C Mignerey,M Mendoza,B Komkov,J M Durham,A Ster,G J Kunde,Y Tanaka,B I Kim,M Finger,R K Choudhury,A Khanzadeev,V Cianciolo,A Lebedev,B Lee,R Wei,A Zelenski,B Hong,P Castera,H Pei,I Ravinovich,M Donadelli,C Vale,T Hachiya,D Yu Peressounko,T Sugitate,S N White,B Azmoun,D Jouan,M Sano,I H Park,M Sarsour,G David,M Vargyas,A Taketani,T Chujo,Iu Mitrankov,A Pun,K Karatsu,C Nattrass,J Rak,B Meredith,S Butsyk,W E Sondheim,M I Nagy,S Yokkaichi,J Lee,D P Morrison,M J Tannenbaum,B Mulilo,M Rosati,K Hashimoto,Y Aramaki,B Love,J L Nagle,Y Riabov,K Shoji,Y I Makdisi,E Haslum,J C Hill,S Miyasaka,M Giles,T Todoroki,D Mcglinchey,M Proissl,H Sako,I Shein,Y Goto,A Iordanova,E Tennant,C Gal,K M Kijima,E Kistenev,D Ivanishchev,B Bannier,M Ouchida,Y Watanabe,J Imrek,R Granier De Cassagnac,T C Awes,J Sziklai,I J Choi,J Murata,S Motschwiller,T Fusayasu,M Stepanov,T Horaguchi,T Novák,S Kaneti,D Sharma,K O Eyser,K A Drees,S Edwards,Y Ikeda,B M Johnson,J Klatsky,M Inaba,C Pinkenburg,A Taranenko,M Kasai,Y.-J Kim,O Dietzsch,T Nakamura,B K Singh,K Ozawa,M Virius,Y Berdnikov,R Vértesi,S F Pate,S Hasegawa,C P Wong,M A L Leite,M Leitgab,D J Kim,J Huang,A Král,V Canoa Roman,H W Van Hecke,R Nouicer,A Deshpande,E.-J Kim,Y Fukao,E M Takagui,K Tanida,M Grosse Perdekamp,Y Ueda,K N Barish,K Okada,Y Miyachi,H Asano,A K Mohanty,S Nagamiya,K S Lee,M Potekhin,V Samsonov,N Novitzky,M L Purschke,B Bassalleck,X R Wang,B H Kang,S H Lee,M Makek,H Pereira,D Kawall,D Reynolds,C.-H Chen,H.-Å Gustafsson,J S Park,W Peng,R Seidl,E Richardson,T Nagae,B Sahlmueller,P Shukla,Z Ji,D Isenhower,Y Corrales Morales,M M Mondal,M Orosz,T K Hemmick,J H Kang,A Durum,Z Sun,M Gonin,M Csanád,L Patel,A Glenn,S Choi,D Silvermyr,E T Atomssa,J Alexander,P Christiansen,D Kotchetkov,J Kapustinsky,V Bumazhnov,Y Kwon,M Mitrankova,N Apadula,T Hester,C L Woody,D Richford,T Murakami,R S Towell,L A Linden Levy,V Babintsev,Y Miake,K Boyle,K Shigaki,H Buesching,G Roche,D V Perepelitsa,K Kurita,Z Wang,S Masumoto,J T Mitchell,K V Dharmawardane,J G Lajoie,N Grau,R Hayano,S K Park,K F Read,R Petti,A Yanovich,D Kotov,T Tsuji,C Mckinney,I Tserruya,X Li,A Datta,A Adare,M Connors,M Tomášek,S Dairaku,O Drapier,W A Zajc,Y Hori,B Fadem,T Ichihara,J Runchey,M Wysocki,A Enokizono,L Ding,S Mohapatra,A V Kazantsev,A Drees,M Kurosawa,R Akimoto,R Takahama,D Blau ,Sanghoon Lim ,Susumu Sato ,Y Yamaguchi ,M Daugherity ,O Chvála ,B Ujvári ,H Al-Ta’ani ,Masayuki Shibata ,Yue Shi Lai ,F Křížek ,T Csörgõ ,C A Aidala ,Mei Bai ,Yusuke Komatsu ,B Jacak ,A Nyanin ,S Fokin ,J Choi ,S P Sørensen ,V.s Borisov ,L B Guo ,C Y ,S Greene ,Kazuo Aoki ,S Lökòs ,K Smith ,Laurent D’orazio ,V K Singh ,K Nakamura ,Z Y You ,B Cole ,X Q He ,A M Sickles ,J C Peng ,Jeongsu Bok ,Daisuke Watanabe ,D S Fitzgerald ,C Maguire ,Z H Citron ,A Öskarsson ,Stephen Baumgart ,E O’brien ,V Manko ,L Kovács ,T A Shibata

doi:10.1103/physrevc.107.024914

Abstract

The measurement of direct photons from Au+Au collisions at sNN=39 and 62.4 GeV in the transverse-momentum range 0.4<pT<3Gev/c is presented by the PHENIX collaboration at the BNLRelativistic Heavy Ion Collider. A significant direct-photon yield is observed in both collision systems. A universal scaling is observed when the direct-photon pT spectra for different center-of-mass energies and for different centrality selections at sNN=62.4 GeV is scaled with (dNch/dη)α for α=1.21±0.04. This scaling also holds true for direct-photon spectra from Au+Au collisions at sNN=200 GeV measured earlier by PHENIX, as well as the spectra from Pb+Pb at sNN=2760 GeV published by ALICE. The scaling power α seems to be independent of pT, center of mass energy, and collision centrality. The spectra from different collision energies have a similar shape up to pT of 2 Gev/c. The spectra have a local inverse slope Teff increasing with pT of 0.174±0.018Gev/c in the range 0.4<pT<1.3Gev/c and increasing to 0.289±0.024Gev/c for 0.9<pT<2.1Gev/c. The observed similarity of low-pT direct-photon production from sNN=39 to 2760 GeV suggests a common source of direct photons for the different collision energies and event centrality selections, and suggests a comparable space-time evolution of direct-photon emission.9 MoreReceived 24 March 2022Accepted 21 October 2022DOI:https://doi.org/10.1103/PhysRevC.107.024914©2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasPhoton, lepton & quark productionRelativistic heavy-ion collisionsTechniquesHadron collidersNuclear Physics

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