Measurements of dielectron production in Au+Au collisions at sNN=27 , 39, and 62.4 GeV from the STAR experiment

M I Abdulhamid,J C Dunlop,J R Adams,S Margetis,G Eppley,M M Aggarwal,T Liu,T Ullrich,Z Wang,G Dale-Gau,M Zyzak,Y Fisyak,P Dixit,M Kelsey,J Seger,T Truhlar,V Prozorova,A Dhamija,I Chakaberia,B S Page,A Das,M Robotkova,T Galatyuk,S Zhou,R Ma,G Wang,A G Knospe,C Y Tsang,F Videbæk,N Smirnov,C Li,L Adamczyk,Y V Khyzhniak,R Reed,P V Shanmuganathan,A Lebedev,A I Sheikh,H Zbroszczyk,W W Jacobs,J Jia,A H Tang,N Xu,A Jentsch,J Putschke,T Pani,K Kang,J H Lee,D Y Shen,C Jena,M Calderón De La Barca Sánchez,K Yip,S Kagamaster,Z Yan,T Nonaka,B Pawlik,X Wu,H J Crawford,J Engelage,F Si,R L Ray,A Ewigleben,D Zhang,S Harabasz,V Verkest,L K Kosarzewski,S W Wissink,Y Su,D P Kikoła,S Fazio,A Hamed,H S Matis,C Zhou,C Perkins,J Chen,P C Weidenkaff,Y Ji,M Stefaniak,Z Ye,J Cheng,A Gupta,Z Tang,K Okubo,N Raha,W Baker,L Ma,J Atchison,F A Flor,B R Pokhrel,Y Wang,N S Lukow,Z Tu,D G Underwood,R Witt,R Bellwied,E C Aschenauer,D Kapukchyan,M Isshiki,H Sako,B Stringfellow,X Z Cai,O D Tsai,M M Mondal,M Posik,G Odyniec,K Shen,N Sharma,R Fatemi,R S Longacre,W Christie,N Herrmann,J H Chen,X Gou,R E Tribble,Q Yang,X Dong,T Shao,H Liu,W Xie,M Daugherity,H Z Huang,C Liu,P Seyboth,K Mi,I Vassiliev,P Tribedy,M Csanád,D Tlusty,J Pan,Z Liu,L Ruan,T Niida,S Esumi,E Duckworth,Y Wu,B Huang,X Wang,B K Chan,G Liu,D J Stewart,T Lin,R Lacey,Y Yu,C Racz,M Nie,I Aggarwal,S Trentalange,I Upsal,D Neff,J D Brandenburg,L Di Carlo,Z Zhang,K Gopal,M I Nagy,H G Ritter,M L Kabir,A Chatterjee,J Adam,Z Xu,D Keane,J L Drachenberg,A Gibson,H Caines,T D S Stanislaus,Y Sun,A K Pandey,C Fu,J M Landgraf,R Sharma,A Tamis,G Mcnamara,M A Rosales Aguilar,X Chu,Z Chang,S Zhang,F Liu,Z W Sweger,S Salur,Y Liu,B E Aboona,Y Zhang,A Quintero,A R Timmins,B Surrow,X Zhu,C Markert,G Wilks,C Sun,Y Song,N Magdy,S Singha,V Bairathi,H Wieman,G Van Buren,W J Llope,C Zhang,M J Skoby,D M Anderson,N K Pruthi,Z Ahammed,L Kumar,A K Sahoo,M D Harasty,X Ju,C A Gagliardi,R Nishitani,Z Chen,J Pluta,B Mohanty,J Zhang,P Bhagat,G D Westfall,I Mooney,J S Wang,Y Han,L Yi,Y Xu,Md Nasim,J C Webb,C Yang,X Huang,P Chaloupka,D Isenhower,D B Nemes,S Oh,T J Humanic,O Eyser,W Zha,D Roy,B A Trzeciak,T Tarnowsky,O Evdokimov,S K Radhakrishnan,A Pandav,J Zhao,C Hu,F Wang,Y Söhngen,T Protzman,G Xie,M Zhao,E Finch,S Aslam,J H Thomas,S Yang,P Huck,W Li,I Kisel,T Todoroki,D Mallick,J Ceska,S Kabana,D Wielanek,X Li,S Choudhury,Q Hu,W B Schmidke,L Liu,D Grosnick,R Pak,D Chen,A Paul,D Cebra,H W Ke,P Sinha,H Harrison-Smith,Y Li,J M Nelson,R Licenik,B Kimelman,S S Shi,Y Feng,B Srivastava,K Kauder,Y Liang,D Kincses,X Liang,O Lomicky,M A Lisa,Y Huang,A Bhasin,Y Zhou,Y Guo,J Lauret,I M Deppner,Z J Zhang,L Didenko,J D Nam,A Ogawa,S Kumar,X Liu,W He,E G Judd,T Huang,L Holub,H S Ko,A S Nain,N Shah,S Mioduszewski,D Kalinkin,Z Li,Y H Leung,W Guryn,B Xi,A Kiselev,A Mukherjee,J W Harris,N Schmitz,R Seto,W Zhang,H Qiu,X Zhang,L Kramárik ,X M Sun ,F J M Geurts ,E Loyd ,S Voloshin ,C.a Tomkiel ,Xiao Zhang ,N A Lewis ,Yugang Ma ,C Feng ,Yifan Hu ,Feng Zhao ,Yan Gao ,S Huang ,H S Xu ,P Chowdhury ,Ashish Jalotra ,J B Singh ,Yanmeng Shi ,J M Butterworth ,K N Barish ,J Bielčík ,Yilin Cheng ,J Mazer ,N Sahoo ,F Seck ,Z H Qin ,J Bielčíková ,M Żurek ,Q Xu ,Yang He ,Raghav Kunnawalkam Elayavalli ,Yang Yu ,Nirmal Ghimire ,X Luo ,P Szymański ,M Šumbera ,Charles W Robertson ,J Vaněk ,J Ball ,Jin Chen ,Susumu Sato ,Alexandre Alarcon Do Passo Suaide ,Meenakshi Sharma ,Q Shou ,Somadutta Bhatta ,D Pawłowska ,Seema Sharma ,Jing Zhou ,Jin Wu ,T Ljubičić ,M Przybycień ,X He ,Tingting Lu

doi:10.1103/physrevc.107.l061901

Abstract

We report systematic measurements of dielectron (e+e−) invariant-mass Mee spectra at midrapidity in Au+Au collisions at sNN = 27, 39, and 62.4 GeV taken with the STAR detector at the Relativistic Heavy Ion Collider. For all energies studied, a significant excess yield of dielectrons is observed in the low-mass region (0.40<Mee<0.75 MeV/c2) compared to hadronic cocktail simulations at freeze-out. Models that include an in-medium broadening of the ρ-meson spectral function consistently describe the observed excess. In addition, we report acceptance-corrected dielectron-excess spectra for Au+Au collisions at midrapidity (|yee|< 1) in the 0–80% centrality bin for each collision energy. The integrated excess yields for 0.4<Mee<0.75GeV/c2, normalized by the charged particle multiplicity at midrapidity, are compared with previously published measurements for Au+Au at sNN1 = 19.6 and 200 GeV. Models that include an in-medium broadening of the ρ-meson spectral function consistently describe the observed excess. The normalized excess yields in the low-mass region show no significant collision energy dependence. The data, however, are consistent with model calculations that demonstrate a modest energy dependence.Received 27 February 2023Accepted 4 May 2023DOI:https://doi.org/10.1103/PhysRevC.107.L061901©2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle & resonance productionRelativistic heavy-ion collisionsNuclear Physics

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