https://doi.org/10.1140/epjc/s2006-02616-5
Experimental Physics
Measurement of charm and beauty dijet cross sections in photoproduction at HERA using the H1 vertex detector
1
I. Physikalisches Institut, RWTH, Aachen, Germany
2
School of Physics and Astronomy, University of Birmingham, Birmingham, UK
3
Inter-University Institute for High Energies ULB-VUB, Brussels, Universiteit Antwerpen, Antwerpen, Belgium
4
Rutherford Appleton Laboratory, Chilton, Didcot, UK
5
Institute for Nuclear Physics, Cracow, Poland
6
Institut für Physik, Universität Dortmund, Dortmund, Germany
7
Joint Institute for Nuclear Research, Dubna, Russia
8
CEA, DSM/DAPNIA, CE-Saclay, Gif-sur-Yvette, France
9
DESY, Hamburg, Germany
10
Institut für Experimentalphysik, Universität Hamburg, Hamburg, Germany
11
Max-Planck-Institut für Kernphysik, Heidelberg, Germany
12
Physikalisches Institut, Universität Heidelberg, Heidelberg, Germany
13
Kirchhoff-Institut für Physik, Universität Heidelberg, Heidelberg, Germany
14
Institut für Experimentelle und Angewandte Physik, Universität Kiel, Kiel, Germany
15
Institute of Experimental Physics, Slovak Academy of Sciences, Kosice, Slovak Republic
16
Department of Physics, University of Lancaster, Lancaster, UK
17
Department of Physics, University of Liverpool, Liverpool, UK
18
Queen Mary and Westfield College, London, UK
19
Physics Department, University of Lund, Lund, Sweden
20
Physics Department, University of Manchester, Manchester, UK
21
CPPM, CNRS/IN2P3, Univ. Mediterranee, Marseille, France
22
Departamento de Fisica Aplicada, CINVESTAV, Merida, Yucatan, Mexico
23
Departamento de Fisica, CINVESTAV, Merida, Mexico
24
Institute for Theoretical and Experimental Physics, Moscow, Russia
25
Lebedev Physical Institute, Moscow, Russia
26
Max-Planck-Institut für Physik, München, Germany
27
LAL, Université de Paris-Sud 11, IN2P3-CNRS, Orsay, France
28
LLR, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France
29
LPNHE, Universités Paris VI and VII, IN2P3-CNRS, Paris, France
30
Faculty of Science, University of Montenegro, Podgorica, Serbia and Montenegro
31
Institute of Physics, Academy of Sciences of the Czech Republic, Praha, Czech Republic
32
Faculty of Mathematics and Physics, Charles University, Praha, Czech Republic
33
Dipartimento di Fisica, Universitá di Roma Tre and INFN Roma 3, Roma, Italy
34
Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria
35
Paul Scherrer Institut, Villigen, Switzerland
36
Fachbereich C, Universität Wuppertal, Wuppertal, Germany
37
Yerevan Physics Institute, Yerevan, Armenia
38
DESY, Zeuthen, Germany
39
Institut für Teilchenphysik, ETH, Zürich, Switzerland
40
Physik-Institut, Universität Zürich, Zürich, Switzerland
41
Physics Department, National Technical University, Zografou Campus, 15773, Athens, Greece
42
Rechenzentrum, Universität Wuppertal, Wuppertal, Germany
43
University of P.J. Safárik, Kosice, Slovak Republic
44
CERN, Geneva, Switzerland
45
Max-Planck-Institut für Physik, München, Germany
46
Comenius University, Bratislava, Slovak Republic
Received:
9
May
2006
Revised:
13
June
2006
Published online:
26
July
2006
A measurement of charm and beauty dijet photoproduction cross sections at the ep collider HERA is presented. Events are selected with two or more jets of transverse momentum pt jet1(2)>11(8) GeV in the central range of pseudo-rapidity -0.9<ηjet1(2)<1.3. The fractions of events containing charm and beauty quarks are determined using a method based on the impact parameter, in the transverse plane, of tracks to the primary vertex, as measured by the H1 central vertex detector. Differential dijet cross sections for charm and beauty, and their relative contributions to the flavour inclusive dijet photoproduction cross section, are measured as a function of the transverse momentum of the leading jet, the average pseudo-rapidity of the two jets and the observable xγ obs. Taking into account the theoretical uncertainties, the charm cross sections are consistent with a QCD calculation in next-to-leading order, while the predicted cross sections for beauty production are somewhat lower than the measurement.
© Springer-Verlag, 2006