Eur. Phys. J. C (2007) 52: 515-530
https://doi.org/10.1140/epjc/s10052-007-0418-0

Regular Article - Experimental Physics

Forward-jet production in deep inelastic ep scattering at HERA

¹ Argonne National Laboratory, Argonne, Illinois, 60439-4815, USA
² Andrews University, Berrien Springs, Michigan, 49104-0380, USA
³ Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany
⁴ University and INFN Bologna, Bologna, Italy
⁵ Physikalisches Institut, Universität Bonn, Bonn, Germany
⁶ H.H. Wills Physics Laboratory, University of Bristol, Bristol, UK
⁷ Physics Department and INFN, Calabria University, Cosenza, Italy
⁸ Chonnam National University, Kwangju, South Korea
⁹ Jabatan Fizik, Universiti Malaya, 50603, Kuala Lumpur, Malaysia
¹⁰ Nevis Laboratories, Columbia University, Irvington on Hudson, New York, 10027, USA
¹¹ The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland
¹² Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Cracow, Poland
¹³ Department of Physics, Jagellonian University, Cracow, Poland
¹⁴ Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
¹⁵ Deutsches Elektronen-Synchrotron DESY, Zeuthen, Germany
¹⁶ University and INFN Florence, Florence, Italy
¹⁷ Fakultät für Physik, Universität Freiburg i.Br., Freiburg i.Br., Germany
¹⁸ Department of Physics and Astronomy, University of Glasgow, Glasgow, UK
¹⁹ Department of Engineering in Management and Finance, Univ. of Aegean, Mytilene, Greece
²⁰ Institute of Exp. Physics, Hamburg University, Hamburg, Germany
²¹ High Energy Nuclear Physics Group, Imperial College London, London, UK
²² Institute of Particle and Nuclear Studies, KEK, Tsukuba, Japan
²³ Institute of Physics and Technology, Ministry of Education and Science of Kazakhstan, Almaty, Kazakhstan
²⁴ Institute for Nuclear Research, National Academy of Sciences and Kiev National University, Kiev, Ukraine
²⁵ Center for High Energy Physics, Kyungpook National University, Daegu, South Korea
²⁶ Institut de Physique Nucléaire, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
²⁷ Departamento de Física Teórica, Universidad Autónoma de Madrid, Madrid, Spain
²⁸ Department of Physics, McGill University, Montréal, Québec, H3A 2T8, Canada
²⁹ Faculty of General Education, Meiji Gakuin University, Yokohama, Japan
³⁰ Moscow Engineering Physics Institute, Moscow, Russia
³¹ Institute of Nuclear Physics, Moscow State University, Moscow, Russia
³² Max-Planck-Institut für Physik, München, Germany
³³ NIKHEF and University of Amsterdam, Amsterdam, The Netherlands
³⁴ Physics Department, Ohio State University, Columbus, Ohio, 43210, USA
³⁵ Department of Physics, University of Oxford, Oxford, UK
³⁶ Dipartimento di Fisica dell’ Università and INFN, Padova, Italy
³⁷ Department of Physics, Pennsylvania State University, University Park, Pennsylvania, 16802, USA
³⁸ Polytechnic University, Sagamihara, Japan
³⁹ Dipartimento di Fisica, Università ’La Sapienza’ and INFN, Rome, Italy
⁴⁰ Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, UK
⁴¹ Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics, Tel-Aviv University, Tel-Aviv, Israel
⁴² Department of Physics, Tokyo Institute of Technology, Tokyo, Japan
⁴³ Department of Physics, University of Tokyo, Tokyo, Japan
⁴⁴ Department of Physics, Tokyo Metropolitan University, Tokyo, Japan
⁴⁵ Università di Torino and INFN, Torino, Italy
⁴⁶ Università del Piemonte Orientale, Novara, and INFN, Torino, Italy
⁴⁷ Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7, Canada
⁴⁸ Physics and Astronomy Department, University College London, London, UK
⁴⁹ Institute of Experimental Physics, Warsaw University, Warsaw, Poland
⁵⁰ Institute for Nuclear Studies, Warsaw, Poland
⁵¹ Department of Particle Physics, Weizmann Institute, Rehovot, Israel
⁵² Department of Physics, University of Wisconsin, Madison, Wisconsin, 53706, USA
⁵³ Department of Physics, York University, York, Ontario, M3J 1P3, Canada
⁵⁴ University College London, London, UK
⁵⁵ Humboldt University, Berlin, Germany
⁵⁶ Univ. Libre de Bruxelles, Bruxelles, Belgium
⁵⁷ DESY group FEB, Hamburg, Germany
⁵⁸ Stanford Linear Accelerator Center, Stanford, USA
⁵⁹ University of Liverpool, Liverpool, UK
⁶⁰ Institut of Theoretical and Experimental Physics, Moscow, Russia
⁶¹ INP, Cracow, Poland
⁶² FPACS, AGH-UST, Cracow, Poland
⁶³ DESY, Hamburg, Germany
⁶⁴ CERN, Geneva, Switzerland
⁶⁵ University of Tokyo, Tokyo, Japan
⁶⁶ Kobe University, Kobe, Japan
⁶⁷ Max Planck Institute, Munich, Germany
⁶⁸ KEK, Tsukuba, Japan
⁶⁹ Nagoya University, Nagoya, Japan
⁷⁰ Łódź University, Łódź, Poland

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

Received: 26 July 2007
Published online: 3 October 2007

Abstract

Forward jet cross sections have been measured in neutral current deep inelastic scattering at low Bjorken-x with the ZEUS detector at HERA using an integrated luminosity of 81.8 pb^-1. Measurements are presented for inclusive forward jets as well as for forward jets accompanied by a dijet system. The explored phase space, with jet pseudorapidity up to 4.3 is expected to be particularly sensitive to the dynamics of QCD parton evolution at low x. The measurements are compared to fixed-order QCD calculations and to leading-order parton-shower Monte Carlo models.