Dielectron and heavy-quark production in inelastic and high-multiplicity proton-proton collisions at root s=13 TeV

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http://hdl.handle.net/10138/298831

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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 , ' Dielectron and heavy-quark production in inelastic and high-multiplicity proton-proton collisions at root s=13 TeV ' , Physics Letters B , vol. 788 , pp. 505-518 . https://doi.org/10.1016/j.physletb.2018.11.009

Title: Dielectron and heavy-quark production in inelastic and high-multiplicity proton-proton collisions at root s=13 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
Date: 2019-01-10
Language: eng
Number of pages: 14
Belongs to series: Physics Letters B
ISSN: 0370-2693
URI: http://hdl.handle.net/10138/298831
Abstract: The measurement of dielectron production is presented as a function of invariant mass and transverse momentum (p(T)) at midrapidity (vertical bar ye vertical bar < 0.8) in proton-proton (pp) collisions at a centre-of-mass energy of root s = 13 TeV. The contributions from light-hadron decays are calculated from their measured cross sections in pp collisions at root s = 7 TeV or 13 TeV. The remaining continuum stems from correlated semileptonic decays of heavy-flavour hadrons. Fitting the data with templates from two different MC event generators, PYTHIA and POWHEG, the charm and beauty cross sections at midrapidity are extracted for the first time at this collision energy: d sigma(c<(c)over bar>)/dy vertical bar(y=0) = 974 +/- 138 (stat.) +/- 140 (syst.) +/- 214(BR) mu b and d sigma(b (b) over bar)/dy vertical bar(y=0) = 79 +/- 14 (stat.) +/- 11 (syst.) +/- 5(BR) mu b using PYTHIA simulations and d sigma(c (c) over bar)/dy vertical bar(y=0) = 1417 +/- 184 (stat.) +/- 204 (syst.) +/- 312(BR) mu b and d sigma(b (b) over bar)/dy vertical bar(y=0) = 48 +/- 14 (stat.) +/- 7 (syst.) +/- 3(BR) mu b for POWHEG. These values, whose uncertainties are fully correlated between the two generators, are consistent with extrapolations from lower energies. The different results obtained with POWHEG and PYTHIA imply different kinematic correlations of the heavy-quark pairs in these two generators. Furthermore, comparisons of dielectron spectra in inelastic events and in events collected with a trigger on high charged-particle multiplicities are presented in various p(T) intervals. The differences are consistent with the already measured scaling of light-hadron and open-charm production at high charged-particle multiplicity as a function of p(T). Upper limits for the contribution of virtual direct photons are extracted at 90% confidence level and found to be in agreement with pQCD calculations. (C) 2018 The Author. Published by Elsevier B.V.
Subject: 114 Physical sciences
PLUS AU COLLISIONS
PB-PB COLLISIONS
PP COLLISIONS
TRANSVERSE-MOMENTUM
PHOTON PRODUCTION
ROOT-S(NN)=200 GEV
J/PSI PRODUCTION
MESON PRODUCTION
COLLECTIVITY
DEPENDENCE
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