Physics Letters B (Nov 2015)

Energy dependence of acceptance-corrected dielectron excess mass spectrum at mid-rapidity in Au+Au collisions at sNN=19.6 and 200 GeV

  • L. Adamczyk,
  • J.K. Adkins,
  • G. Agakishiev,
  • M.M. Aggarwal,
  • Z. Ahammed,
  • I. Alekseev,
  • J. Alford,
  • A. Aparin,
  • D. Arkhipkin,
  • E.C. Aschenauer,
  • G.S. Averichev,
  • A. Banerjee,
  • R. Bellwied,
  • A. Bhasin,
  • A.K. Bhati,
  • P. Bhattarai,
  • J. Bielcik,
  • J. Bielcikova,
  • L.C. Bland,
  • I.G. Bordyuzhin,
  • J. Bouchet,
  • A.V. Brandin,
  • I. Bunzarov,
  • T.P. Burton,
  • J. Butterworth,
  • H. Caines,
  • M. Calder'on de la Barca S'anchez,
  • J.M. Campbell,
  • D. Cebra,
  • M.C. Cervantes,
  • I. Chakaberia,
  • P. Chaloupka,
  • Z. Chang,
  • S. Chattopadhyay,
  • J.H. Chen,
  • X. Chen,
  • J. Cheng,
  • M. Cherney,
  • W. Christie,
  • M.J.M. Codrington,
  • G. Contin,
  • H.J. Crawford,
  • S. Das,
  • L.C. De Silva,
  • R.R. Debbe,
  • T.G. Dedovich,
  • J. Deng,
  • A.A. Derevschikov,
  • B. di Ruzza,
  • L. Didenko,
  • C. Dilks,
  • X. Dong,
  • J.L. Drachenberg,
  • J.E. Draper,
  • C.M. Du,
  • L.E. Dunkelberger,
  • J.C. Dunlop,
  • L.G. Efimov,
  • J. Engelage,
  • G. Eppley,
  • R. Esha,
  • O. Evdokimov,
  • O. Eyser,
  • R. Fatemi,
  • S. Fazio,
  • P. Federic,
  • J. Fedorisin,
  • Feng,
  • P. Filip,
  • Y. Fisyak,
  • C.E. Flores,
  • L. Fulek,
  • C.A. Gagliardi,
  • D. Garand,
  • F. Geurts,
  • A. Gibson,
  • M. Girard,
  • L. Greiner,
  • D. Grosnick,
  • D.S. Gunarathne,
  • Y. Guo,
  • S. Gupta,
  • A. Gupta,
  • W. Guryn,
  • A. Hamad,
  • A. Hamed,
  • R. Haque,
  • J.W. Harris,
  • L. He,
  • S. Heppelmann,
  • A. Hirsch,
  • G.W. Hoffmann,
  • D.J. Hofman,
  • S. Horvat,
  • H.Z. Huang,
  • X. Huang,
  • B. Huang,
  • P. Huck,
  • T.J. Humanic,
  • G. Igo,
  • W.W. Jacobs,
  • H. Jang,
  • K. Jiang,
  • E.G. Judd,
  • S. Kabana,
  • D. Kalinkin,
  • K. Kang,
  • K. Kauder,
  • H.W. Ke,
  • D. Keane,
  • A. Kechechyan,
  • Z.H. Khan,
  • D.P. Kikola,
  • I. Kisel,
  • A. Kisiel,
  • S.R. Klein,
  • D.D. Koetke,
  • T. Kollegger,
  • L.K. Kosarzewski,
  • L. Kotchenda,
  • A.F. Kraishan,
  • P. Kravtsov,
  • K. Krueger,
  • I. Kulakov,
  • L. Kumar,
  • R.A. Kycia,
  • M.A.C. Lamont,
  • J.M. Landgraf,
  • K.D. Landry,
  • J. Lauret,
  • A. Lebedev,
  • R. Lednicky,
  • J.H. Lee,
  • X. Li,
  • X. Li,
  • W. Li,
  • Z.M. Li,
  • Y. Li,
  • C. Li,
  • M.A. Lisa,
  • F. Liu,
  • T. Ljubicic,
  • W.J. Llope,
  • M. Lomnitz,
  • R.S. Longacre,
  • X. Luo,
  • L. Ma,
  • R. Ma,
  • G.L. Ma,
  • Y.G. Ma,
  • N. Magdy,
  • R. Majka,
  • A. Manion,
  • S. Margetis,
  • C. Markert,
  • H. Masui,
  • H.S. Matis,
  • D. McDonald,
  • K. Meehan,
  • N.G. Minaev,
  • S. Mioduszewski,
  • B. Mohanty,
  • M.M. Mondal,
  • D.A. Morozov,
  • M.K. Mustafa,
  • B.K. Nandi,
  • Md. Nasim,
  • T.K. Nayak,
  • G. Nigmatkulov,
  • L.V. Nogach,
  • S.Y. Noh,
  • J. Novak,
  • S.B. Nurushev,
  • G. Odyniec,
  • A. Ogawa,
  • K. Oh,
  • V. Okorokov,
  • D.L. Olvitt Jr.,
  • B.S. Page,
  • Y.X. Pan,
  • Y. Pandit,
  • Y. Panebratsev,
  • T. Pawlak,
  • B. Pawlik,
  • H. Pei,
  • C. Perkins,
  • A. Peterson,
  • P. Pile,
  • M. Planinic,
  • J. Pluta,
  • N. Poljak,
  • K. Poniatowska,
  • J. Porter,
  • M. Posik,
  • A.M. Poskanzer,
  • N.K. Pruthi,
  • J. Putschke,
  • H. Qiu,
  • A. Quintero,
  • S. Ramachandran,
  • R. Raniwala,
  • S. Raniwala,
  • R.L. Ray,
  • H.G. Ritter,
  • J.B. Roberts,
  • O.V. Rogachevskiy,
  • J.L. Romero,
  • A. Roy,
  • L. Ruan,
  • J. Rusnak,
  • O. Rusnakova,
  • N.R. Sahoo,
  • P.K. Sahu,
  • I. Sakrejda,
  • S. Salur,
  • A. Sandacz,
  • J. Sandweiss,
  • A. Sarkar,
  • J. Schambach,
  • R.P. Scharenberg,
  • A.M. Schmah,
  • W.B. Schmidke,
  • N. Schmitz,
  • J. Seger,
  • P. Seyboth,
  • N. Shah,
  • E. Shahaliev,
  • P.V. Shanmuganathan,
  • M. Shao,
  • M.K. Sharma,
  • B. Sharma,
  • W.Q. Shen,
  • S.S. Shi,
  • Q.Y. Shou,
  • E.P. Sichtermann,
  • R. Sikora,
  • M. Simko,
  • M.J. Skoby,
  • N. Smirnov,
  • D. Smirnov,
  • D. Solanki,
  • L. Song,
  • P. Sorensen,
  • H.M. Spinka,
  • B. Srivastava,
  • T.D.S. Stanislaus,
  • R. Stock,
  • M. Strikhanov,
  • B. Stringfellow,
  • M. Sumbera,
  • B.J. Summa,
  • Y. Sun,
  • Z. Sun,
  • X.M. Sun,
  • X. Sun,
  • B. Surrow,
  • D.N. Svirida,
  • M.A. Szelezniak,
  • J. Takahashi,
  • A.H. Tang,
  • Z. Tang,
  • T. Tarnowsky,
  • A.N. Tawfik,
  • J.H. Thomas,
  • A.R. Timmins,
  • D. Tlusty,
  • M. Tokarev,
  • S. Trentalange,
  • R.E. Tribble,
  • P. Tribedy,
  • S.K. Tripathy,
  • B.A. Trzeciak,
  • O.D. Tsai,
  • T. Ullrich,
  • D.G. Underwood,
  • I. Upsal,
  • G. Van Buren,
  • G. van Nieuwenhuizen,
  • M. Vandenbroucke,
  • R. Varma,
  • A.N. Vasiliev,
  • R. Vertesi,
  • F. Videbaek,
  • Y.P. Viyogi,
  • S. Vokal,
  • S.A. Voloshin,
  • A. Vossen,
  • Y. Wang,
  • F. Wang,
  • H. Wang,
  • J.S. Wang,
  • G. Wang,
  • Y. Wang,
  • J.C. Webb,
  • G. Webb,
  • L. Wen,
  • G.D. Westfall,
  • H. Wieman,
  • S.W. Wissink,
  • R. Witt,
  • Y.F. Wu,
  • Z. Xiao,
  • W. Xie,
  • K. Xin,
  • Z. Xu,
  • Q.H. Xu,
  • N. Xu,
  • H. Xu,
  • Y.F. Xu,
  • Y. Yang,
  • C. Yang,
  • S. Yang,
  • Q. Yang,
  • Y. Yang,
  • Z. Ye,
  • P. Yepes,
  • L. Yi,
  • K. Yip,
  • I.-K. Yoo,
  • N. Yu,
  • H. Zbroszczyk,
  • W. Zha,
  • J.B. Zhang,
  • X.P. Zhang,
  • S. Zhang,
  • J. Zhang,
  • Z. Zhang,
  • Y. Zhang,
  • J.L. Zhang,
  • F. Zhao,
  • J. Zhao,
  • C. Zhong,
  • L. Zhou,
  • X. Zhu,
  • Y. Zoulkarneeva,
  • M. Zyzak

DOI
https://doi.org/10.1016/j.physletb.2015.08.044
Journal volume & issue
Vol. 750, no. C
pp. 64 – 71

Abstract

Read online

The acceptance-corrected dielectron excess mass spectra, where the known hadronic sources have been subtracted from the inclusive dielectron mass spectra, are reported for the first time at mid-rapidity |yee|<1 in minimum-bias Au+Au collisions at sNN=19.6 and 200 GeV. The excess mass spectra are consistently described by a model calculation with a broadened ρ spectral function for Mee<1.1 GeV/c2. The integrated dielectron excess yield at sNN=19.6 GeV for 0.4<Mee<0.75 GeV/c2, normalized to the charged particle multiplicity at mid-rapidity, has a value similar to that in In+In collisions at sNN=17.3 GeV. For sNN=200 GeV, the normalized excess yield in central collisions is higher than that at sNN=17.3 GeV and increases from peripheral to central collisions. These measurements indicate that the lifetime of the hot, dense medium created in central Au+Au collisions at sNN=200 GeV is longer than those in peripheral collisions and at lower energies.