Low-pT e+ e- pair production in Au+Au collisions at √sNN=200 GeV and U+U collisions at √sNN=193 GeV at STAR

• Verfasst von: Adam, Jaroslav [VerfasserIn]
• Verfasst von: Deppner, Ingo Martin [VerfasserIn]
• Verfasst von: Herrmann, Norbert [VerfasserIn]
• Titel: Low-pT e+ e- pair production in Au+Au collisions at √sNN=200 GeV and U+U collisions at √sNN=193 GeV at STAR
• Körperschaft: STAR Collaboration [VerfasserIn]
• Verf.angabe: J. Adam, I.M. Deppner, N. Herrmann [und 347 weitere] (STAR Collaboration)
• E-Jahr: 2018
• Jahr: 25 September 2018
• Umfang: 8 S.
• Fussnoten: Gesehen am 05.07.2019 ; Im Titel steht der Ausdruck "sNN" unter dem Wurzelsymbol, "NN" ist dabei tiefgestellt
• Titel Quelle: Enthalten in: Physical review letters
• Ort Quelle: College Park, Md. : APS, 1958
• Jahr Quelle: 2018
• Band/Heft Quelle: 121(2018,13) Artikel-Nummer 132301, 8 Seiten
• ISSN Quelle: 1079-7114
• DOI: doi:10.1103/PhysRevLett.121.132301
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1668663112

Abstract

We report first measurements of e+e− pair production in the mass region 0.4<Mee<2.6 GeV/c2 at low transverse momentum (pT<0.15 GeV/c) in noncentral Au+Au collisions at √sNN=200 GeV and U+U collisions at √sNN=193 GeV. Significant enhancement factors, expressed as ratios of data over known hadronic contributions, are observed in the 40%-80% centrality of these collisions. The excess yields peak distinctly at low pT with a width (√⟨p2T⟩) between 40 and 60 MeV/c. The absolute cross section of the excess depends weakly on centrality, while those from a theoretical model calculation incorporating an in-medium broadened ρ spectral function and radiation from a quark gluon plasma or hadronic cocktail contributions increase dramatically with an increasing number of participant nucleons. Model calculations of photon-photon interactions generated by the initial projectile and target nuclei describe the observed excess yields but fail to reproduce the p2T distributions.