Article ; Online: Soft-Dielectron Excess in Proton-Proton Collisions at sqrt[s]=13 TeV.
2021 Volume 127, Issue 4, Page(s) 42302
Abstract: A measurement of dielectron production in proton-proton (pp) collisions at sqrt[s]=13 TeV ...
Abstract | A measurement of dielectron production in proton-proton (pp) collisions at sqrt[s]=13 TeV, recorded with the ALICE detector at the CERN LHC, is presented in this Letter. The data set was recorded with a reduced magnetic solenoid field. This enables the investigation of a kinematic domain at low dielectron (ee) invariant mass m_{ee} and pair transverse momentum p_{T,ee} that was previously inaccessible at the LHC. The cross section for dielectron production is studied as a function of m_{ee}, p_{T,ee}, and event multiplicity dN_{ch}/dη. The expected dielectron rate from hadron decays, called hadronic cocktail, utilizes a parametrization of the measured η/π^{0} ratio in pp and proton-nucleus collisions, assuming that this ratio shows no strong dependence on collision energy at low transverse momentum. Comparison of the measured dielectron yield to the hadronic cocktail at 0.15<m_{ee}<0.6 GeV/c^{2} and for p_{T,ee}<0.4 GeV/c indicates an enhancement of soft dielectrons, reminiscent of the "anomalous" soft-photon and soft-dilepton excess in hadron-hadron collisions reported by several experiments under different experimental conditions. The enhancement factor over the hadronic cocktail amounts to 1.61±0.13(stat)±0.17(syst,data)±0.34(syst,cocktail) in the ALICE acceptance. Acceptance-corrected excess spectra in m_{ee} and p_{T,ee} are extracted and compared with calculations of dielectron production from hadronic bremsstrahlung and thermal radiation within a hadronic many-body approach.<br /> |
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Language | English |
Publishing date | 2021-08-06 |
Publishing country | United States |
Document type | Journal Article |
ZDB-ID | 208853-8 |
ISSN | 1079-7114 ; 0031-9007 |
ISSN (online) | 1079-7114 |
ISSN | 0031-9007 |
DOI | 10.1103/PhysRevLett.127.042302 |
Database | MEDical Literature Analysis and Retrieval System OnLINE |
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