München 2019 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 34: Heavy-Ion Collisions and QCD Phases VI
HK 34.3: Talk
Wednesday, March 20, 2019, 14:45–15:00, HS 15
Low-mass dielectron measurements in minimum-bias pp collisions at √s = 5.02 TeV with ALICE — •Leonhardt Viebach and Raphaelle Bailhache for the ALICE collaboration — Institut fuer Kernphysik, Goethe-Universitaet Frankfurt
The production of low-mass dielectrons is the most promising tool for the understanding of the chiral-symmetry restoration and of the thermodynamical properties of the Quark-Gluon plasma (QGP) created in heavy-ion collisions. In the intermediate-mass region, the measurement of thermal dielectrons from the QGP is nevertheless very challenging at the LHC due to the dominant contribution of e+e− pairs from open-charm and -beauty hadron decays. To single out the interesting signal characteristics of the QGP, the primordial e+e− pair production in vacuum needs to be first understood. It can be studied in minimum-bias proton-proton collisions. Dielectron measurements in elementary collision systems serve not only as a reference for the heavy-ion analysis but provide also a test for Monte-Carlo event generators, aiming to reproduce the heavy-flavour production mechanisms.
In this talk, we present the status of the dielectron analysis in pp collisions at √s = 5.02 TeV with ALICE. The dielectron yield is studied as a function of invariant mass, pair transverse momentum, and pair transverse impact parameter (DCAee). The latter helps to disentangle prompt and non-prompt dielectron sources. The results will be compared to the expectations from known hadronic sources and their implications for the heavy-flavour production will be discussed.
Supported by BMBF and the Helmholtz Association.