Phys. Rev. Lett.
82,
3025–3029
(1999)
Observation of a Coherence Length Effect in Exclusive ρ0 Electroproduction
K. Ackerstaff et al. (HERMES Collaboration)
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K. Ackerstaff5, A. Airapetian34, N. Akopov34, I. Akushevich6, M. Amarian34,29,25, E. C. Aschenauer6,13,14,25, H. Avakian10, R. Avakian34, A. Avetissian34, B. Bains15, S. Barrow27, C. Baumgarten23, M. Beckmann12, St. Belostotski28, J. E. Belz4,30,31, Th. Benisch8, S. Bernreuther8, N. Bianchi10, S. Blanchard24, J. Blouw25, H. Böttcher6, A. Borissov6,14, J. Brack4, S. Brauksiepe12, B. Braun8,23, B. Bray3, St. Brons6, W. Brückner14, A. Brüll14, E. E. W. Bruins20, H. J. Bulten18,25,33, R. V. Cadman15, G. P. Capitani10, P. Carter3, P. Chumney24, E. Cisbani29, G. R. Court17, P. F. Dalpiaz9, P. P. J. Delheij31, E. De Sanctis10, D. De Schepper20, E. Devitsin22, P. K. A. de Witt Huberts25, P. Di Nezza10, M. Düren8, A. Dvoredsky3, G. Elbakian34, J. Ely4, J. Emerson30,31, A. Fantoni10, A. Fechtchenko7, M. Ferstl8, D. Fick19, K. Fiedler8, B. W. Filippone3, H. Fischer12, H. T. Fortune27, B. Fox4, S. Frabetti9, J. Franz12, S. Frullani29, M.-A. Funk5, N. D. Gagunashvili7, P. Galumian1, H. Gao2,15,20, Y. Gärber6, F. Garibaldi29, G. Gavrilov28, P. Geiger14, V. Gharibyan34, V. Giordjian10, A. Golendukhin19,34, G. Graw23, O. Grebeniouk28, P. W. Green1,31, L. G. Greeniaus1,31, C. Grosshauser8, M. G. Guidal25, A. Gute8, V. Gyurjyan10, J. P. Haas24, W. Haeberli18, J.-O. Hansen2, D. Hasch6, O. Häusser30,31,*, F. H. Heinsius12, R. S. Henderson31, Th. Henkes25, M. Henoch8, R. Hertenberger23, Y. Holler5, R. J. Holt15, W. Hoprich14, H. Ihssen5,25, M. Iodice29, A. Izotov28, H. E. Jackson2, A. Jgoun28, C. Jones2, R. Kaiser30,31, E. Kinney4, M. Kirsch8, A. Kisselev28, P. Kitching1, H. Kobayashi32, N. Koch19, K. Königsmann12, M. Kolstein25, H. Kolster23, V. Korotkov6, W. Korsch3,16, V. Kozlov22, L. H. Kramer20,11, B. Krause6, V. G. Krivokhijine7, M. Kückes30,31, F. Kümmell12, G. Kyle24, W. Lachnit8, W. Lorenzon27,21, A. Lung3, N. C. R. Makins2,15, F. K. Martens1, J. W. Martin20, F. Masoli9, A. Mateos20, M. McAndrew17, K. McIlhany3, R. D. McKeown3, F. Meissner6, F. Menden12,31, D. Mercer4, A. Metz23, N. Meyners5, O. Mikloukho28, C. A. Miller1,31, M. A. Miller15, R. G. Milner20, V. Mitsyn7, A. Most15,21, R. Mozzetti10, V. Muccifora10, A. Nagaitsev7, Y. Naryshkin28, A. M. Nathan15, F. Neunreither8, M. Niczyporuk20, W.-D. Nowak6, M. Nupieri10, P. Oelwein14, H. Ogami32, T. G. O'Neill2, R. Openshaw31, J. Ouyang31, B. R. Owen15, V. Papavassiliou24, S. F. Pate20,24, M. Pitt3, H. R. Poolman25, S. Potashov22, D. H. Potterveld2, B. Povh14, G. Rakness4, A. Reali9, R. Redwine20, A. R. Reolon10, R. Ristinen4, K. Rith8, H. Roloff6, G. Röper5, P. Rossi10, S. Rudnitsky27, M. Ruh12, D. Ryckbosch13, Y. Sakemi32, I. Savin7, C. Scarlett21, F. Schmidt8, H. Schmitt12, G. Schnell24, K. P. Schüler5, A. Schwind6, J. Seibert12, T.-A. Shibata32, T. Shin20, V. Shutov7, C. Simani9, A. Simon12,24, K. Sinram5, P. Slavich9,10, J. Sowinski14, M. Spengos27,5, E. Steffens8, J. Stenger8, J. Stewart17, F. Stock14,8, U. Stoesslein6, M. Sutter20, H. Tallini17, S. Taroian34, A. Terkulov22, D. M. Thiessen30,31, E. Thomas10, B. Tipton20, A. Trudel30,31, M. Tytgat13, G. M. Urciuoli29, J. J. van Hunen25, R. van de Vyver13, J. F. J. van den Brand18,25,33, G. van der Steenhoven25, M. C. Vetterli30,31, V. Vikhrov28, M. Vincter31, J. Visser25, E. Volk14, W. Wander8, T. P. Welch26, S. E. Williamson15, T. Wise18, T. Wölfel8, K. Woller5, S. Yoneyama32, K. Zapfe-Düren5, H. Zohrabian34, and R. Zurmühle27 (HERMES Collaboration)
1Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada
2Physics Division, Argonne National Laboratory, Argonne, Illinois 60439-4843
3W. K. Kellogg Radiation Lab, California Institute of Technology, Pasadena, California 91125
4Nuclear Physics Laboratory, University of Colorado, Boulder, Colorado 80309-0446
5DESY, Deutsches Elektronen Synchrotron, D-22603 Hamburg, Germany
6DESY Zeuthen, D-15738 Zeuthen, Germany
7Joint Institute for Nuclear Research, 141980 Dubna, Russia
8Physikalisches Institut, Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
9Dipartimento di Fisica, Università di Ferrara, I-44100 Ferrara, Italy
10Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, I-00044 Frascati, Italy
11Department of Physics, Florida International University, Miami, Florida 33199
12Fakultät für Physik, Universität Freiburg, D-79104 Freiburg, Germany
13Department of Subatomic and Radiation Physics, University of Gent, B-9000 Gent, Belgium
14Max-Planck-Institut für Kernphysik, D-69029 Heidelberg, Germany
15Department of Physics, University of Illinois, Urbana, Illinois 61801
16Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506
17Physics Department, University of Liverpool, Liverpool L69 7ZE, United Kingdom
18Department of Physics, University of Wisconsin—Madison, Madison, Wisconsin 53706
19Physikalisches Institut, Philipps-Universität Marburg, D-35037 Marburg, Germany
20Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
21Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109-1120
22Lebedev Physical Institut, 117924 Moscow, Russia
23Sektion Physik, Universität München, D-85748 Garching, Germany
24Department of Physics, New Mexico State University, Las Cruces, New Mexico 88003
25Nationaal Instituut voor Kernfysica en Hoge-Energiefysica (NIKHEF), NL-1009 DB Amsterdam, The Netherlands
26Physics Department, Oregon State University, Corvallis, Oregon 97331
27Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6396
28Petersburg Nuclear Physics Institute, St. Petersburg, 188350 Russia
29Istituto Nazionale di Fisica Nucleare, Sezione Sanità and Physics Laboratory, Istituto Superiore di Sanità, I-00161 Roma, Italy
30Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
31TRIUMF, Vancouver, British Columbia V6T 2A3, Canada
32Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
33Department of Physics and Astronomy, Vrije Universiteit, NL-1081 HV Amsterdam, The Netherlands
34Yerevan Physics Institute, 375036, Yerevan, Armenia
Received 5 November 1998; published in the issue dated 12 April 1999
Exclusive incoherent electroproduction of the ρ0(770) meson from 1H, 2H, 3He, and 14N targets has been studied by the HERMES experiment at squared four-momentum transfer Q2>0.4GeV2 and positron energy loss ν from 9 to 20 GeV. The ratio of the 14N to 1H cross sections per nucleon, known as the nuclear transparency, was found to decrease with increasing coherence length of quark-antiquark fluctuations of the virtual photon. The data provide clear evidence of the interaction of the quark-antiquark fluctuations with the nuclear medium.
© 1999 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.82.3025
DOI:
10.1103/PhysRevLett.82.3025
PACS:
13.60.Le, 14.40.Cs, 24.85.+p, 25.30.Rw
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