Eur. Phys. J. C (2009) 62: 625-658
https://doi.org/10.1140/epjc/s10052-009-1055-6

Regular Article - Experimental Physics

Measurement of high-Q ² neutral current deep inelastic e ⁻ p scattering cross sections with a longitudinally polarised electron beam 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, 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, University of Aegean, Chios, Greece
²² Institute of Experimental 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, H3A 2T8, Canada
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, München, 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, 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, M5S 1A7, Canada
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, Ontario, M3J 1P3, Canada

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

Received: 26 January 2009
Revised: 27 April 2009
Published online: 11 July 2009

Abstract

Measurements of the neutral current cross sections for deep inelastic scattering in e ⁻ p collisions at HERA with a longitudinally polarised electron beam are presented. The single-differential cross-sections d σ/dQ ², d σ/dx and d σ/dy and the double-differential cross sections in Q ² and x are measured in the kinematic region y<0.9 and Q ²>185 GeV ² for both positively and negatively polarised electron beams and for each polarisation state separately. The measurements are based on an integrated luminosity of 169.9 pb ⁻¹ taken with the ZEUS detector in 2005 and 2006 at a centre-of-mass energy of 318 GeV. The structure functions and xF ₃ ^{γ Z} are determined by combining the e ⁻ p results presented in this paper with previously measured e ⁺ p neutral current data. The asymmetry parameter A ⁻ is used to demonstrate the parity violating effects of electroweak interactions at large spacelike photon virtuality. The measurements agree well with the predictions of the Standard Model.