Measurement of dielectron production in central Pb-Pb collisions at root S-NN=2.76 TeV

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The ALICE Collaboration , Acharya , S , Brücken , E J , Chang , B , Hilden , T E , Kim , D J , Litichevskyi , V , Mieskolainen , M M , Orava , R , Parkkila , J E , Rak , J , Räsänen , S S , Saarinen , S , Slupecki , M , Snellman , T W , Trzaska , W H , Vargyas , M & Viinikainen , J 2019 , ' Measurement of dielectron production in central Pb-Pb collisions at root S-NN=2.76 TeV ' , Physical Review C , vol. 99 , no. 2 , 024002 . https://doi.org/10.1103/PhysRevC.99.024002

Title: Measurement of dielectron production in central Pb-Pb collisions at root S-NN=2.76 TeV
Author: The ALICE collaboration; Acharya, S.; Brücken, E. J.; Chang, B.; Hilden, T. E.; Kim, D. J.; Litichevskyi, V.; Mieskolainen, M. M.; Orava, R.; Parkkila, J. E.; Rak, J.; Räsänen, S. S.; Saarinen, S.; Slupecki, M.; Snellman, T. W.; Trzaska, W. H.; Vargyas, M.; Viinikainen, J.
Contributor: University of Helsinki, Helsinki Institute of Physics
University of Helsinki, University of Jyväskylä
University of Helsinki, Helsinki Institute of Physics
University of Helsinki, University of Jyväskylä
University of Helsinki, Helsinki Institute of Physics
University of Helsinki, Helsinki Institute of Physics
University of Helsinki, Helsinki Institute of Physics
University of Helsinki, University of Jyväskylä
University of Helsinki, Helsinki Institute of Physics
University of Helsinki, University of Jyväskylä
University of Helsinki, University of Jyväskylä
University of Helsinki, University of Jyväskylä
Date: 2019-02-14
Language: eng
Number of pages: 23
Belongs to series: Physical Review C
ISSN: 2469-9985
URI: http://hdl.handle.net/10138/300491
Abstract: The first measurement of dielectron (e(+)e(-)) production in central (0-10%) Pb-Pb collisions at root S-NN = 2.76 TeV at the LHC is presented. The dielectron invariant-mass spectrum is compared to the expected contributions from hadron decays in the invariant-mass range 0 < m(ee) < 3.5 GeV/c(2). The ratio of data and the cocktail of hadronic contributions without vacuum rho(0) is measured in the invariant-mass range 0.15 < m(ee) < 0.7 GeV/c(2), where an excess of dielectrons is observed in other experiments, and its value is 1.40 +/- 0.28 (stat.) +/- 0.08 (syst.) +/- 0.27 (cocktail). The dielectron spectrum measured in the invariant mass range 0 < m(ee) < 1 GeV/c(2) is consistent with the predictions from two theoretical model calculations that include thermal dielectron production from both partonic and hadronic phases with in-medium broadened rho(0) meson. The fraction of direct virtual photons over inclusive virtual photons is extracted for dielectron pairs with invariant mass 0.1 < m(ee) < 0.3 GeV/c(2) and in the transverse-momentum intervals 1 <( )p(T,ee) < 2 GeV/c and 2 < p(T,ee) < 4 GeV/c. The measured fraction of virtual direct photons is consistent with the measurement of real direct photons by ALICE and with the expectations from previous dielectron measurements at RHIC within the experimental uncertainties.
Subject: 114 Physical sciences
DIRECT PHOTON PRODUCTION
S-W INTERACTIONS
AU COLLISIONS
RHO-MESON
DIMUON PRODUCTION
PAIR PRODUCTION
PP
J/PSI
ENHANCEMENT
EMISSION
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