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dc.contributor.authorAcharya, Shreyasipt_BR
dc.contributor.authorGay Ducati, Maria Beatrizpt_BR
dc.contributor.authorPereira, Luis Gustavopt_BR
dc.contributor.authorPezzi, Rafael Perettipt_BR
dc.contributor.authorALICE Collaborationpt_BR
dc.date.accessioned2018-11-22T02:49:08Zpt_BR
dc.date.issued2018pt_BR
dc.identifier.issn1029-8479pt_BR
dc.identifier.urihttp://hdl.handle.net/10183/184932pt_BR
dc.description.abstractThe rst measurement of e+e􀀀 pair production at mid-rapidity (j ej < 0.8) in pp collisions at p s = 7TeV with ALICE at the LHC is presented. The dielectron production is studied as a function of the invariant mass (mee < 3.3 GeV/c2), the pair transverse momentum (pT;ee < 8 GeV/c), and the pair transverse impact parameter (DCAee), i.e., the average distance of closest approach of the reconstructed electron and positron tracks to the collision vertex, normalised to its resolution. The results are compared with the expectations from a cocktail of known hadronic sources and are well described when PYTHIA is used to generate the heavy- avour contributions. In the low-mass region (0:14 < mee < 1:1 GeV/c2), prompt and non-prompt e+e􀀀 sources can be separated via the DCAee. In the intermediate-mass region (1.1 < mee < 2.7 GeV/c2), a double-di erential t to the data in mee and pT;ee and a t of the DCAee distribution allow the total cc and bb cross sections to be extracted. Two di erent event generators, PYTHIA and POWHEG, can reproduce the shape of the two-dimensional mee and pT;ee spectra, as well as the shape of the DCAee distribution, reasonably well. However, di erences in the cc and bb cross sections are observed when using the generators to extrapolate to full phase space. Finally, the ratio of inclusive to decay photons is studied via the measurement of virtual direct photons in the transverse-momentum range 1 < pT < 8 GeV/c. This is found to be unity within the statistical and systematic uncertainties and consistent with expectations from next-to-leading order perturbative quantum chromodynamic calculations.en
dc.format.mimetypeapplication/pdfpt_BR
dc.language.isoengpt_BR
dc.relation.ispartofThe journal of high energy physics. Trieste. No. 9 (Sept. 2018), 064, 46 p.pt_BR
dc.rightsOpen Accessen
dc.subjectAceleradores de partículaspt_BR
dc.subjectHeavy Ion Experimentsen
dc.subjectColisões proton-protonpt_BR
dc.titleDielectron production in proton-proton collisions at √s = 7 TeVpt_BR
dc.typeArtigo de periódicopt_BR
dc.identifier.nrb001080828pt_BR
dc.type.originEstrangeiropt_BR


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