Darmstadt 2016 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 2: Heavy Ion Collision and QCD Phases I
HK 2.7: Vortrag
Montag, 14. März 2016, 15:45–16:00, S1/01 A01
Charm and beauty contributions in the dilepton invariant mass spectrum in pp collisions measured with ALICE — •Sebastian Scheid, Raphaelle Bailhache, and Harald Appelshäuser for the ALICE collaboration — Institut für Kernphysik, Goethe-Universität Frankfurt
The main purpose of ALICE at the LHC is to investigate the properties of the deconfined state of strongly-interacting matter, the Quark Gluon Plasma (QGP), produced in high-energy heavy-ion collisions. Since leptons experience negligible final-state interactions, they are well suited to study the properties of the medium. A measurement of the thermal radiation from the QGP in the dielectron intermediate mass region will allow to estimate the medium temperature. In this region the main background is due to correlated semi-leptonic decays of B- and D-Mesons. They have the particularity to have a large decay length of about 500µ m for B-Mesons and 100-300µ m for D-Mesons. Therefore the reconstructed tracks of heavy-flavour decay electrons do not point to the primary vertex of the collision. Combining the measured distance of closest approach of each single electron into a pair variable DCAee gives the possibility to separate prompt di-electron pairs from the heavy-quark background.
The analysis in pp collisions allows to study the feasability of extracting the heavy-quark production with the current ITS of ALICE and provides a reference for Pb−Pb collisions. In this presentation, first results on the DCAee spectra in pp collisions at 7 TeV will be shown and compared to reference distributions from MC simulations.