https://doi.org/10.1007/BF01245799
Measurement of the diffractive structure functionF 2 D(4) at HERA
1
Argonne National Laboratory, Argonne, IL, USA
2
Andrews University, Berrien Springs, MI, USA
3
University and INFN Bologna, Bologna, Italy
4
Physikalisches Institut der Universität Bonn, Bonn, Germany
5
H.H. Wills Physics Laboratory, University of Bristol, Bristol, UK
6
Physics Department and INFN, Calabria University, Cosenza, Italy
7
Chonnam National University, Kwangju, Korea
8
Nevis Labs., Columbia University, Irvington on Hudson, N.Y., USA
9
Institute of Nuclear Physics, Cracow, Poland
10
Faculty of Physics and Nuclear Techniques, Academy of Mining and Metallurgy, Cracow, Poland
11
Department of Physics, Jagellonian Univ., Cracow, Poland
12
Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
13
DESY-IfH Zeuthen, Zeuthen, Germany
14
University and INFN, Florence, Italy
15
Laboratori Nazionali di Frascati, INFN, Frascati, Italy
16
Fakultät für Physik der Universität Freiburg i.Br., Freiburg i.Br., Germany
17
Department of Physics and Astronomy, University of Glasgow, Glasgow, UK
18
Hamburg University, I. Institute of Experimental Physics, Hamburg, Germany
19
Hamburg University, II. Institute of Experimental Phsyics, Hamburg, Germany
20
Imperial College London, High Energy Nuclear Physics Group, London, UK
21
Physics and Astronomy Department, University of Iowa, Iowa City, USA
22
Forschungszentrum Jülich, Institut für Kernphysik, Jülich, Germany
23
Institute of Particle and Nuclear Studies, KEK, Tsukuba, Japan
24
Korea University, Seoul, Korea
25
Depto de Física Teórica, Universidad Autónoma Madrid, Madrid, Spain
26
Department of Physics, McGill University, Montréal, Québec, Canada
27
Faculty of General Education, Meiji Gakuin University, Yokohama, Japan
28
Moscow Engineering Physics Institute, Moscow, Russia
29
Institute of Nuclear Physics, Moscow State University, Moscow, Russia
30
NIKHEF and University of Amsterdam, Amsterdam, Netherlands
31
Physics Department, Ohio State University, Columbus, Ohio, USA
32
Department of Physics, University of Oxford, Oxford, UK
33
Dipartimento di Fisica dell' University and INFN, Padova, Italy
34
Department of Physics, Pennsylvania State University, University Park, PA, USA
35
Polytechnic University, Sagamihara, Japan
36
Dipartimento di Fisica, Univ. ‘La Sapienza’ and INFN, Rome, Italy
37
Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, UK
38
University of California, Santa Cruz, CA, USA
40
Fachbereich Physik der Universität-Gesamthochschule, Siegen, Germany
41
Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics, Tel-Aviv University, Tel-Aviv, Israel
42
Department of Physics, University of Tokyo, Tokyo, Japan
43
Department of Physics, Tokyo Metropolitan University, Tokyo, Japan
44
Dipartimento di Fisica Sperimentale and INFN, University di Torino, Torino, Italy
45
II Faculty of Sciences, Torino University and INFN, Alessandria, Italy
46
Department of Physics, University of Toronto, Toronto, Ont., Canada
47
Physics and Astronomy Department, University College London, London, UK
48
Institute of Experimental Physics, Warsaw University, Warsaw, Poland
49
Institute for Nuclear Studies, Warsaw, Poland
50
Department of Particle Physics, Weizmann Institute, Rehovot, Israel
51
Department of Physics, University of Wisconsin, Madison, WI, USA
52
Department of Physics, York University, North York, Ont., Canada
Received:
17
September
1997
Published online:
27
February
2005
This paper presents the first analysis of diffractive photon dissociation events in deep inelastic positron-proton scattering at HERA in which the proton in the final state is detected and its momentum measured. The events are selected by requiring a scattered proton in the ZEUS leading proton spectrometer (LPS) with χ L > 0.97, where xL is the fraction of the incoming proton beam momentum carried by the scattered proton. The use of the LPS significantly reduces the contamination from events with diffractive dissociation of the proton into low mass states and allows a direct measurement of t, the square of the four-momentum exchanged at the proton vertex. The dependence of the cross section ont is measured in the interval 0.073 < |t| < 0.4 GeV2 and is found to be described by an exponential shape with the slope parameterb = 7.2 ± 1.1(stat.) −0.9 +0.7 (syst.) GeV−2. The diffractive structure function FD (4) is presented as 0.9 a function of χ H ≃ 1 − χ L and β, the momentum fraction of the struck quark with respect to χ H , and averaged over thet interval 0.073 < |t′ < 0.4 GeV2 and the photon virtuality range 5 <Q 2 < 20 GeV2. In the kinematic range 4 × 104 < χ p < 0.03 and 0.015 < β < 0.5, the χ p dependence ofF D(4) is fitted with a form (1/χ p )α , yieldinga − 1.00 ± 0.09 (stat.) −0.05 +0.11 (syst.). Upon integration overL, the structure functionF 2 D(3) is determined in a kinematic range extending to higher χ p and lower β compared to our previous analysis; the results are discussed within the framework of Regge theory.
© Springer-Verlag, 1998