Eur. Phys. J. C (2007) 50: 1-20
https://doi.org/10.1140/epjc/s10052-006-0206-2

Regular Article - Experimental Physics

Diffractive open charm production in deep-inelastic scattering and photoproduction at HERA

¹ I. Physikalisches Institut der RWTH, Aachen, Germany
² Vinca Institute of Nuclear Sciences, Belgrade, Serbia
³ School of Physics and Astronomy, University of Birmingham, Birmingham, UK
⁴ Inter-University Institute for High Energies ULB-VUB, Brussels, Belgium
⁵ Universiteit Antwerpen, Antwerpen, Belgium
⁶ Rutherford Appleton Laboratory, Chilton, Didcot, UK
⁷ Institute for Nuclear Physics, Cracow, Poland
⁸ Institut für Physik, Universität Dortmund, Dortmund, Germany
⁹ Joint Institute for Nuclear Research, Dubna, Russia
¹⁰ CEA, DSM/DAPNIA, CE-Saclay, Gif-sur-Yvette, France
¹¹ DESY, Hamburg, Germany
¹² Institut für Experimentalphysik, Universität Hamburg, Hamburg, Germany
¹³ Max-Planck-Institut für Kernphysik, Heidelberg, Germany
¹⁴ Physikalisches Institut, Universität Heidelberg, Heidelberg, Germany
¹⁵ Kirchhoff-Institut für Physik, Universität Heidelberg, Heidelberg, Germany
¹⁶ Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovak Republic
¹⁷ Department of Physics, University of Lancaster, Lancaster, UK
¹⁸ Department of Physics, University of Liverpool, Liverpool, UK
¹⁹ Queen Mary and Westfield College, London, UK
²⁰ Physics Department, University of Lund, Lund, Sweden
²¹ Physics Department, University of Manchester, Manchester, UK
²² CPPM, CNRS/IN2P3, Univ. Mediterranee, Marseille, France
²³ Departamento de Fisica Aplicada, CINVESTAV, Merida, Yucatan, Mexico
²⁴ Departamento de Fisica, CINVESTAV, Merida, Mexico
²⁵ Institute for Theoretical and Experimental Physics, Moscow, Russia
²⁶ Lebedev Physical Institute, Moscow, Russia
²⁷ Max-Planck-Institut für Physik, München, Germany
²⁸ LAL, Universite de Paris-Sud 11, IN2P3-CNRS, Orsay, France
²⁹ LLR, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France
³⁰ LPNHE, Universites Paris VI and VII, IN2P3-CNRS, Paris, France
³¹ Faculty of Science, University of Montenegro, Podgorica, Montenegro
³² Institute of Physics, Academy of Sciences of the Czech Republic, Praha, Czech Republic
³³ Faculty of Mathematics and Physics, Charles University, Praha, Czech Republic
³⁴ Dipartimento di Fisica Universita di Roma Tre and INFN Roma 3, Roma, Italy
³⁵ Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria
³⁶ Institute of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
³⁷ Paul Scherrer Institut, Villigen, Switzerland
³⁸ Fachbereich C, Universität Wuppertal, Wuppertal, Germany
³⁹ Yerevan Physics Institute, Yerevan, Armenia
⁴⁰ DESY, Zeuthen, Germany
⁴¹ Institut für Teilchenphysik, ETH, Zürich, Switzerland
⁴² Physik-Institut der Universität Zürich, Zürich, Switzerland
⁴³ Physics Department, National Technical University, Zografou Campus, 15773, Athens, Greece
⁴⁴ Rechenzentrum, Universität Wuppertal, Wuppertal, Germany
⁴⁵ University of P.J. Safarik, Kosice, Slovak Republic
⁴⁶ CERN, Geneva, Switzerland
⁴⁷ Max-Planck-Institut für Physik, München, Germany
⁴⁸ Comenius University, Bratislava, Slovak Republic
⁴⁹ Helmholtz Humboldt Research Award, DESY and University Hamburg, Hamburg, Germany

^* e-mail: obehnke@mail.desy.de

Received: 25 October 2006
Revised: 24 November 2006
Published online: 8 February 2007

Abstract

Measurements are presented of diffractive open charm production at HERA. The event topology is given by ep→eXY where the system X contains at least one charmed hadron and is well separated by a large rapidity gap from a leading low-mass proton remnant system Y. Two analysis techniques are used for the cross section measurements. In the first, the charm quark is tagged by the reconstruction of a D^*±(2010) meson. This technique is used in deep-inelastic scattering (DIS) and photoproduction (γp). In the second, a method based on the displacement of tracks from the primary vertex is used to measure the open charm contribution to the inclusive diffractive cross section in DIS. The measurements are compared with next-to-leading order QCD predictions based on diffractive parton density functions previously obtained from a QCD analysis of the inclusive diffractive cross section at H1. A good agreement is observed in the full kinematic regime, which supports the validity of QCD factorization for open charm production in diffractive DIS and γp.