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HK: Fachverband Physik der Hadronen und Kerne

HK 3: Schwerionenkollisionen und QCD Phasen

HK 3.2: Vortrag

Montag, 4. März 2013, 11:30–11:45, HSZ-201

Measurement of B meson production in pp collisions at √s = 2.76 TeV and √s = 7 TeV via displaced electrons in ALICE — •Markus Heide — WWU Münster

Measurements of the production cross section of B mesons in pp collisions in ALICE are important in two respects. They allow to test perturbative quantum chromodynamics calculations, and they provide an essential reference for comparison with studies in heavy-ion collisions at high energies, in which a hot and dense medium, the quark-gluon plasma (QGP), is created. When passing through this medium, quarks lose energy via the strong interaction. Since the amount of energy loss is expected to depend significantly on the quark mass, beauty as the heaviest observable flavour is of particular interest for the exploration of QGP properties. The measurement of electrons from beauty hadron decays at mid-rapidity will be presented for √s = 2.76 TeV and √s = 7 TeV. First, the electron identification in the ALICE central barrel, using the Time Projection Chamber (TPC) and Time Of Flight (TOF) detector, will be outlined. An explanation of the selection of electrons from beauty hadron decays with a large impact parameter will be given. It makes use of the B mesons’ larger decay length (≈ 500 µ m) in comparison to D mesons and other background sources. The remaining electron background in the selected sample is estimated based on calculations using ALICE measured p_t spectra. The resulting B meson p_t spectra measured in pp collisions at √s = 7 TeV in 2010 and at √s = 2.76 TeV in 2011 will be shown.