Eur. Phys. J. C (2009) 63: 527-548
https://doi.org/10.1140/epjc/s10052-009-1090-3

Regular Article - Experimental Physics

Subjet distributions in deep inelastic scattering at HERA

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

^* e-mail: tobias.haas@desy.de

Received: 7 February 2009
Revised: 13 May 2009
Published online: 27 August 2009

Abstract

Subjet distributions were measured in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 81.7 pb⁻¹. Jets were identified using the k _T cluster algorithm in the laboratory frame. Subjets were defined as jet-like substructures identified by a reapplication of the cluster algorithm at a smaller value of the resolution parameter . Measurements of subjet distributions for jets with exactly two subjets for are presented as functions of observables sensitive to the pattern of parton radiation and to the colour coherence between the initial and final states. Perturbative QCD predictions give an adequate description of the data.