Observation of Exclusive Deeply Virtual Compton Scattering in Polarized Electron Beam Asymmetry Measurements
S. StepanyanChristopher Newport University, Newport News, Virginia 23606Volker BurkertThomas Jefferson National Accelerator Facility, Newport News, Virginia 23606L. ElouadrhiriChristopher Newport University, Newport News, Virginia 23606G. S. AdamsRensselaer Polytechnic Institute, Department of Physics, Troy, New York 12181E. AnciantCEA Saclay, DAPNIA-SPhN, F91191 Gif-sur-Yvette Cedex, FranceM. AnghinolfiIstituto Nazionale di Fisica Nucleare, Sezione di Genova e Dipartimento di Fisica dell'Universita, 16146 Genova, ItalyB. AsavapibhopUniversity of Massachusetts, Department of Physics, Amherst, Massachusetts 01003G. AuditCEA Saclay, DAPNIA-SPhN, F91191 Gif-sur-Yvette Cedex, FranceT. AugerCEA Saclay, DAPNIA-SPhN, F91191 Gif-sur-Yvette Cedex, FranceH. AvakianIstituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, C.P. 13, 00044 Frascati, ItalyJ. BallArizona State University, Department of Physics and Astronomy, Tempe, Arizona 85287S. BarrowFlorida State University, Department of Physics, Tallahassee, Florida 32306M. BattaglieriIstituto Nazionale di Fisica Nucleare, Sezione di Genova e Dipartimento di Fisica dell'Universita, 16146 Genova, ItalyK. BeardJames Madison University, Department of Physics, Harrisonburg, Virginia 22807M. BektasogluOld Dominion University, Department of Physics, Norfolk, Virginia 23529P.Y. BertinUniversity Blaise Pascal/IN2P3, Aubiere Cedex, FranceN. BianchiIstituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, C.P. 13, 00044 Frascati, ItalyA. S. BiselliRensselaer Polytechnic Institute, Department of Physics, Troy, New York 12181S. BoiarinovInstitute of Theoretical and Experimental Physics, Moscow, 117259, RussiaB. E. BonnerRice University, T.W. Bonner Nuclear Laboratory, Houston, Texas 77005-1892S. BouchignyInstitut de Physique Nucleaire d'Orsay, IN2P3, BP 1, 91406 Orsay, FranceD. BranfordEdinburgh University, Department of Physics and Astronomy, Edinburgh EH9 3JZ, United KingdomW. K. BrooksThomas Jefferson National Accelerator Facility, Newport News, Virginia 23606J. R. CalarcoUniversity of New Hampshire, Department of Physics, Durham, New Hampshire 03824D. S. CarmanOhio University, Department of Physics, Athens, Ohio 45701B. CarnahanCatholic University of America, Department of Physics, Washington, D.C. 20064L. CicianiOld Dominion University, Department of Physics, Norfolk, Virginia 23529P. L. ColeThomas Jefferson National Accelerator Facility, Newport News, Virginia 23606Alan ColemanCollege of William and Mary, Department of Physics, Williamsburg, Virginia 23185D. CordsThomas Jefferson National Accelerator Facility, Newport News, Virginia 23606P. CorvisieroIstituto Nazionale di Fisica Nucleare, Sezione di Genova e Dipartimento di Fisica dell'Universita, 16146 Genova, ItalyDonald G. CrabbUniversity of Virginia, Department of Physics, Charlottesville, Virginia 22903H. CrannellCatholic University of America, Department of Physics, Washington, D.C. 20064J. CummingsRensselaer Polytechnic Institute, Department of Physics, Troy, New York 12181Pavel DegtiarenkoThomas Jefferson National Accelerator Facility, Newport News, Virginia 23606H. DenizliUniversity of Pittsburgh, Department of Physics, Pittsburgh, Pennsylvania 15260L. C. DennisFlorida State University, Department of Physics, Tallahassee, Florida 32306E. De SanctisIstituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, C.P. 13, 00044 Frascati, ItalyR. DeVitaIstituto Nazionale di Fisica Nucleare, Sezione di Genova e Dipartimento di Fisica dell'Universita, 16146 Genova, ItalyK. V. DharmawardaneOld Dominion University, Department of Physics, Norfolk, Virginia 23529C. DjalaliUniversity of South Carolina, Department of Physics, Columbia, South Carolina 29208G. E. DodgeOld Dominion University, Department of Physics, Norfolk, Virginia 23529D. DoréCEA Saclay, DAPNIA-SPhN, F91191 Gif-sur-Yvette Cedex, FranceD. DoughtyChristopher Newport University, Newport News, Virginia 23606P. DragovitschFlorida State University, Department of Physics, Tallahassee, Florida 32306S. DytmanUniversity of Pittsburgh, Department of Physics, Pittsburgh, Pennsylvania 15260M. EckhauseCollege of William and Mary, Department of Physics, Williamsburg, Virginia 23185H. EgiyanCollege of William and Mary, Department of Physics, Williamsburg, Virginia 23185K. S. EgiyanYerevan Physics Institute, 375036 Yerevan, ArmeniaA. EmplRensselaer Polytechnic Institute, Department of Physics, Troy, New York 12181R. FatemiUniversity of Virginia, Department of Physics, Charlottesville, Virginia 22903R. J. FeuerbachCarnegie Mellon University, Department of Physics, Pittsburgh, Pennsylvania 15213J. FicenecVirginia Polytechnic Institute and State University, Department of Physics, Blacksburg, Virginia 24061K. FissumT. A. ForestOld Dominion University, Department of Physics, Norfolk, Virginia 23529A. FreybergerOld Dominion University, Department of Physics, Norfolk, Virginia 23529H. O. FunstenCollege of William and Mary, Department of Physics, Williamsburg, Virginia 23185S. J. GaffDuke University, Physics Department, Durham, North Carolina 27706M. GaiUniversity of Connecticut, Physics Department, Storrs, Connecticut 06269M. GarçonCEA Saclay, DAPNIA-SPhN, F91191 Gif-sur-Yvette Cedex, FranceG. GavalianYerevan Physics Institute, 375036 Yerevan, ArmeniaS. GiladG. P. GilfoyleUniversity of Richmond, Department of Physics, Richmond, Virginia 23173K. L. GiovanettiJames Madison University, Department of Physics, Harrisonburg, Virginia 22807P. GirardUniversity of South Carolina, Department of Physics, Columbia, South Carolina 29208K. A. GriffioenCollege of William and Mary, Department of Physics, Williamsburg, Virginia 23185M. GuidalInstitut de Physique Nucleaire d'Orsay, IN2P3, BP 1, 91406 Orsay, FranceM. GuilloUniversity of South Carolina, Department of Physics, Columbia, South Carolina 29208V. GyurjyanThomas Jefferson National Accelerator Facility, Newport News, Virginia 23606C. HadjidakisInstitut de Physique Nucleaire d'Orsay, IN2P3, BP 1, 91406 Orsay, FranceJ. HardieChristopher Newport University, Newport News, Virginia 23606D. HeddleChristopher Newport University, Newport News, Virginia 23606F. W. HersmanUniversity of New Hampshire, Department of Physics, Durham, New Hampshire 03824K. HicksOhio University, Department of Physics, Athens, Ohio 45701R. S. HicksUniversity of Massachusetts, Department of Physics, Amherst, Massachusetts 01003M. HoltropUniversity of New Hampshire, Department of Physics, Durham, New Hampshire 03824J. F. HuRensselaer Polytechnic Institute, Department of Physics, Troy, New York 12181C. E. Hyde-WrightOld Dominion University, Department of Physics, Norfolk, Virginia 23529M. M. ItoThomas Jefferson National Accelerator Facility, Newport News, Virginia 23606D. JenkinsVirginia Polytechnic Institute and State University, Department of Physics, Blacksburg, Virginia 24061K. JooUniversity of Virginia, Department of Physics, Charlottesville, Virginia 22903J. H. KelleyDuke University, Physics Department, Durham, North Carolina 27706M. KhandakerNorfolk State University, Norfolk, Virginia 23504D. H. KimKyungpook National University, Department of Physics, Taegu 702-701, South KoreaK. KimKyungpook National University, Department of Physics, Taegu 702-701, South KoreaK. Y. KimKyungpook National University, Department of Physics, Taegu 702-701, South KoreaW. KimKyungpook National University, Department of Physics, Taegu 702-701, South KoreaA. KleinOld Dominion University, Department of Physics, Norfolk, Virginia 23529F. J. KleinThomas Jefferson National Accelerator Facility, Newport News, Virginia 23606M. KlusmanRensselaer Polytechnic Institute, Department of Physics, Troy, New York 12181M. KossovInstitute of Theoretical and Experimental Physics, Moscow, 117259, RussiaL. H. KramerFlorida International University, Department of Physics, Miami, Florida 33199S. E. KuhnOld Dominion University, Department of Physics, Norfolk, Virginia 23529J. M. LagetCEA Saclay, DAPNIA-SPhN, F91191 Gif-sur-Yvette Cedex, FranceDavid LawrenceUniversity of Massachusetts, Department of Physics, Amherst, Massachusetts 01003A. LonghiCatholic University of America, Department of Physics, Washington, D.C. 20064K. LukashinThomas Jefferson National Accelerator Facility, Newport News, Virginia 23606J. J. ManakThomas Jefferson National Accelerator Facility, Newport News, Virginia 23606C. MarchandCEA Saclay, DAPNIA-SPhN, F91191 Gif-sur-Yvette Cedex, FranceS. McAleerFlorida State University, Department of Physics, Tallahassee, Florida 32306
2001en
ABI
Annotatsiya
We report the first results of the beam-spin asymmetry measured in the reaction $\stackrel{\ensuremath{\rightarrow}}{e}p\ensuremath{\rightarrow}\mathrm{ep}\ensuremath{\gamma}$ at a beam energy of 4.25 GeV. A large asymmetry with a $\mathrm{sin}\ensuremath{\varphi}$ modulation is observed, as predicted for the interference term of deeply virtual compton scattering (DVCS) and the Bethe-Heitler process. The amplitude of this modulation is $\ensuremath{\alpha}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.202\ifmmode\pm\else\textpm\fi{}0.028$. In leading-order and leading-twist perturbative QCD, the $\ensuremath{\alpha}$ is directly proportional to the imaginary part of the DVCS amplitude.
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