Bochum 2018 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 31: Heavy Ion Collisions and QCD Phases V
HK 31.5: Vortrag
Mittwoch, 28. Februar 2018, 15:15–15:30, HZO 60
Dielectron production in pp collisions at √s=13 TeV measured in a dedicated low magnetic-field setting with ALICE — •Jerome Jung for the ALICE collaboration — Goethe Universität, IKF, Frankfurt am Main, Deutschland
Low-mass dielectrons are an important probe for the hot and dense medium which is created in ultra-relativistic heavy-ion collisions. Since leptons do not interact strongly and are produced throughout the whole collision process, they carry information from all collision stages with negligible final-state interaction.
The ALICE detector is well-suited to perform this measurement due to its excellent tracking and particle identification capabilities at low momenta. However, Dalitz decays and photon conversions lead to a high combinatorial background. Therefore, the minimization of the background is a key aspect of this analysis. The reconstruction efficiency of low-pT electrons can be increased by reducing the magnetic field of the central barrel solenoid. This allows a better rejection of the electron background and simultaneously gives the opportunity to increase the accessible phase space.
In this talk, the status of the dielectron measurement in pp collisions at √s = 13 TeV from pilot runs taken with B=0.2 T in the ALICE central barrel will be presented. The results will be compared to reference data recorded with the nominal field. Finally, the invariant-mass and pair-transverse-momentum distributions will be compared to the expected yield from known hadronic sources.
Supported by BMBF and the Helmholtz Association.