Darmstadt 2016 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 40: Heavy Ion Collision and QCD Phases IX
HK 40.2: Vortrag
Mittwoch, 16. März 2016, 17:00–17:15, S1/01 A01
Beauty-jet tagging using the track counting method in pp collisions with ALICE at the LHC — •Linus Feldkamp for the ALICE collaboration — Westfälische Wilhelms-Universität Münster
Charm and beauty quarks, produced in the early stage of heavy-ion collisions, are ideal probes to study the characteristics of the hot and dense deconfined medium (Quark-Gluon Plasma) formed in these collisions. The radiative energy loss of high energy partons interacting with the medium is expected to be larger for gluons than for quarks, and to depend on the quark mass, with beauty quarks losing less energy than charm quarks, light quarks and gluons. Therefore, a comparison of the modification in the momentum distribution or possibly in the jet shape of beauty-jets with that of light flavour or c-jets in Pb-Pb collisions relative to pp collisions allows to investigate the mass dependence of the energy loss. It also allows to study the redistribution of the lost energy and possible modifications to b-quark fragmentation in the medium. The track counting method exploits the large rφ-impact parameters, d0, of B-meson decay products to identify beauty-jets. The signed rφ-impact parameter, d0 = sign(d0→ · pjet→) d0, is calculated for each track in the jet cone, where d0→ is pointing away from the primary vertex. The distribution of the n-th largest d0 in a jet is sensitive to the flavor of the hadronizing parton and allows to select jets coming form beauty on a statistical basis. In this contribution, we give an overview of the beauty jet measurement using the track counting method with ALICE in pp collisions at √s = 7 TeV that will serve as baseline reference for future energy loss studies.