Soft-dielectron excess in proton-proton collisions at √s=13 TeV

A measurement of dielectron production in proton-proton (pp) collisions at √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 dielectro...

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Hauptverfasser: Acharya, Shreyasi (VerfasserIn) , Angelov, Venelin (VerfasserIn) , Arslandok, Mesut (VerfasserIn) , Danisch, Meike (VerfasserIn) , Feuillard, Victor (VerfasserIn) , Glässel, Peter (VerfasserIn) , Kim, Jiyoung (VerfasserIn) , Kim, Minjung (VerfasserIn) , Köhler, Markus Konrad (VerfasserIn) , Leardini, Lucia (VerfasserIn) , López, Jorge (VerfasserIn) , Martin, Nicole Alice (VerfasserIn) , Ohlson, Alice (VerfasserIn) , Pachmayer, Yvonne C. (VerfasserIn) , Reygers, Klaus (VerfasserIn) , Schicker, Rainer (VerfasserIn) , Schmah, Alexander (VerfasserIn) , Schmidt, Marten Ole (VerfasserIn) , Stachel, Johanna (VerfasserIn) , Stiefelmaier, Stephan (VerfasserIn) , Windelband, Bernd (VerfasserIn) , Yüncü, Alperen (VerfasserIn)
Körperschaft: ALICE (VerfasserIn)
Dokumenttyp: Article (Journal)
Sprache:Englisch
Veröffentlicht: 23 July 2021
In: Physical review letters
Year: 2021, Jahrgang: 127, Heft: 4, Pages: 1-13
ISSN:1079-7114
DOI:10.1103/PhysRevLett.127.042302
Online-Zugang:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1103/PhysRevLett.127.042302
Verlag, lizenzpflichtig, Volltext: https://link.aps.org/doi/10.1103/PhysRevLett.127.042302
Volltext
Verfasserangaben:S. Acharya et al., (A Large Ion Collider Experiment Collaboration)
Beschreibung
Zusammenfassung:A measurement of dielectron production in proton-proton (pp) collisions at √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 mee and pair transverse momentum pT,ee that was previously inaccessible at the LHC. The cross section for dielectron production is studied as a function of mee, pT,ee, and event multiplicity dNch/dη. The expected dielectron rate from hadron decays, called hadronic cocktail, utilizes a parametrization of the measured η/π0 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<mee<0.6 GeV/c2 and for pT,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 mee and pT,ee are extracted and compared with calculations of dielectron production from hadronic bremsstrahlung and thermal radiation within a hadronic many-body approach.
Beschreibung:(A Large Ion Collider Experiment Collaboration): S. Acharya, V. Anguelov, M. Arslandok, M.C. Danisch, V.J.G. Feuillard, P. Glässel, J. Kim, M. Kim, M.K. Köhler, L. Leardini, J.A. Lopez, N.A. Martin, A. Ohlson, Y. Pachmayer, K. Reygers, R. Schicker, A. Schmah, M.O. Schmidt, J. Stachel, S.F. Stiefelmaier, B. Windelband, A. Yuncu [und viele weitere]
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Beschreibung:Online Resource
ISSN:1079-7114
DOI:10.1103/PhysRevLett.127.042302