Speaker
Karin Daum
(University of Wuppertal/DESY)
Description
The cross section for ep -> e b\bar{b} X in photoproduction is measured with the H1 detector at the ep-collider HERA. The decay channel b\bar{b} -> ee X' is selected by identifying the semi-electronic decays of the b-quarks. The total production cross section is measured in the kinematic range given by the photon virtuality Q^2 <= 1 GeV^2, the inelasticity 0.05 <= y <= 0.65 and the pseudorapidity of the b-quarks |eta(b)|,|eta(\bar{b})| <= 2. The differential production cross section is measured as a function of the average transverse momentum of the beauty quarks < P_T(b) > down to the threshold. The results are compared to next-to-leading-order QCD predictions.
Measurements of cross sections for beauty and charm events with dijets and a muon in the photoproduction regime at HERA are presented. The data were collected with the H1 detector and correspond to an integrated luminosity of 179 pb^{-1}. Events with dijets of transverse momentum P_T^{jet1} > 7 GeV and P_T^{jet2} > 6 GeV in the pseudorapidity range -1.5< \eta^{jet} < 2.5 in the laboratory frame are selected in the kinematic region of photon virtuality Q^2 < 2.5 GeV^2 and inelasticity 0.2 < y < 0.8. One of the two selected jets must be associated to a muon with P_T^{\mu} > 2.5 GeV in the pseudorapidity range -1.3 < \eta^{\mu} < 1.5. The fractions of beauty and charm events are determined using the impact parameters of the muon tracks with respect to the primary vertex and their transverse momentum relative to the axis of the associated jet. Both variables are reconstructed using the H1 vertex detector. The measurements are in agreement with QCD predictions at leading and next-to-leading order.
Author
. H1 Collaboration
(DESY)
