Gluon polarization in the nucleon from quasi-real photoproduction of high-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:msub><mml:mi>p</mml:mi><mml:mi mathvariant="normal">T</mml:mi></mml:msub></mml:math> hadron pairs
E.S. AgeevInstitute for High Energy Physics, State Research Center of the Russian Federation, 142281 Protvino, RussiaV. AlexakhinJoint Institute for Nuclear Research, Dubna, RussiaYu. AlexandrovP.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow, RussiaG. D. AlexeevJoint Institute for Nuclear Research, Dubna, RussiaA. AmorosoUniversity of Turin, Turin, ItalyB. BadełekUniversity of Warsaw, Warsaw, PolandF. BalestraUniversity of Turin, Turin, ItalyJ. BallCEA DAPNIA/SPhN Saclay, 91191 Gif-sur-Yvette, FranceG. BaumBielefeld University, Bielefeld, GermanyY. BedferCEA DAPNIA/SPhN Saclay, 91191 Gif-sur-Yvette, FranceP. BerglundLow Temperature Laboratory, Helsinki University of Technology, 02015 HUT, and Helsinki Institute of Physics, University of Helsinki, 00014 Helsinki, FinlandC. BernetEuropean Organization for Nuclear Research, Geneva, SwitzerlandR. BertiniUniversity of Turin, Turin, ItalyR. BirsaUniversity of Trieste, Trieste, ItalyJ. BisplinghoffUniversity of Bonn, Bonn, GermanyP. BordaloFundação para a Ciência e Tecnologia, Lisbon, PortugalF. BradamanteUniversity of Trieste, Trieste, ItalyA. BravarJohannes Gutenberg University Mainz, Mainz, GermanyA. BressanUniversity of Trieste, Trieste, ItalyG. BronaUniversity of Warsaw, Warsaw, PolandE. BurtinINFN Trieste and Department of Physics, University of Trieste, 34127 Trieste, ItalyM.P. BussaUniversity of Turin, Turin, ItalyV. BytchkovJoint Institute for Nuclear Research, Dubna, RussiaL. CeriniUniversity of Trieste, Trieste, ItalyA. ChapiróThe Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, ItalyA. CicuttinThe Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, ItalyM. ColantoniUniversity of Turin, Turin, ItalyA. ColavitaThe Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, ItalyS. CostaUniversity of Turin, Turin, ItalyM.L. CrespoThe Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, ItalyS. Dalla TorreUniversity of Trieste, Trieste, ItalyS. DasguptaINFN Trieste and Department of Physics, University of Trieste, 34127 Trieste, ItalyN. DedekLudwig-Maximilians-Universität München, Munich, GermanyR. De MasiTechnical University of Munich, Munich, GermanyО. ДенисовUniversity of Turin, Turin, ItalyL. Dhara) Also at University of East Piedmont, 15100 Alessandria, ItalyV. DiazThe Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, ItalyA.M. DinkelbachTechnical University of Munich, Munich, GermanyA. Dolgopolov) Also at University of East Piedmont, 15100 Alessandria, ItalyS.V. Donskov) Also at University of East Piedmont, 15100 Alessandria, ItalyV. A. Dorofeev) Also at University of East Piedmont, 15100 Alessandria, ItalyN. DoshitaNagoya University, Nagoya, JapanV. DuicUniversity of Trieste, Trieste, ItalyW. DünnweberLudwig-Maximilians-Universität München, Munich, GermanyJ. EhlersHeidelberg University, Heidelberg, GermanyP.D. EversheimUniversity of Bonn, Bonn, GermanyW. EyrichFriedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, GermanyM. FabroUniversity of Trieste, Trieste, ItalyM. FaesslerLudwig-Maximilians-Universität München, Munich, GermanyV. FalaleevEuropean Organization for Nuclear Research, Geneva, SwitzerlandP. FaulandBielefeld University, Bielefeld, GermanyA. FerreroUniversity of Turin, Turin, ItalyL. FerreroUniversity of Turin, Turin, ItalyМ. ФингерCharles University, Prague, CzechiaH. FischerUniversity of Freiburg, Freiburg im Breisgau, GermanyJ. FranzUniversity of Freiburg, Freiburg im Breisgau, GermanyJ.M. FriedrichTechnical University of Munich, Munich, GermanyV. FrolovUniversity of Turin, Turin, ItalyR. GarfagniniUniversity of Turin, Turin, ItalyF. GautheronBielefeld University, Bielefeld, GermanyO.P. GavrichtchoukJoint Institute for Nuclear Research, Dubna, RussiaS. GerassimovTechnical University of Munich, Munich, GermanyR. GeyerLudwig-Maximilians-Universität München, Munich, GermanyM. GiorgiUniversity of Trieste, Trieste, ItalyB. GobboUniversity of Trieste, Trieste, ItalyS. GoertzUniversity of Bonn, Bonn, GermanyA.M. GorinINFN Trieste and Department of Physics, University of Trieste, 34127 Trieste, ItalyO.A. GrajekUniversity of Warsaw, Warsaw, PolandA. GrassoUniversity of Turin, Turin, ItalyB. GrubeTechnical University of Munich, Munich, GermanyA. GrünemaierUniversity of Freiburg, Freiburg im Breisgau, GermanyJ. HannappelUniversity of Bonn, Bonn, GermanyD. von HarrachJohannes Gutenberg University Mainz, Mainz, GermanyT. HasegawaMinistry of Education, Culture, Sports, Science and Technology, Tokyo, JapanS. HedickeUniversity of Freiburg, Freiburg im Breisgau, GermanyF. H. HeinsiusEuropean Organization for Nuclear Research, Geneva, SwitzerlandR. HermannJohannes Gutenberg University Mainz, Mainz, GermanyC. HeßCERN, 1211 Geneva 23, SwitzerlandF. HinterbergerUniversity of Bonn, Bonn, GermanyM. von HodenbergUniversity of Freiburg, Freiburg im Breisgau, GermanyN. HorikawaNagoya University, Nagoya, JapanS. HorikawaEuropean Organization for Nuclear Research, Geneva, SwitzerlandN. d׳Hose) Also at University of East Piedmont, 15100 Alessandria, ItalyR. IjaduolaThe Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, ItalyC. IlgnerLudwig-Maximilians-Universität München, Munich, GermanyA.I. IoukaevJoint Institute for Nuclear Research, Dubna, RussiaS. IshimotoNagoya University, Nagoya, JapanO. IvanovJoint Institute for Nuclear Research, Dubna, RussiaT. IwataNagoya University, Nagoya, JapanR. JahnUniversity of Bonn, Bonn, GermanyA. JanataJoint Institute for Nuclear Research, Dubna, RussiaR. JoostenUniversity of Bonn, Bonn, GermanyN.I. JouravlevJoint Institute for Nuclear Research, Dubna, RussiaE. KabußJohannes Gutenberg University Mainz, Mainz, GermanyV. KalinnikovUniversity of Trieste, Trieste, ItalyD. KangUniversity of Freiburg, Freiburg im Breisgau, GermanyF. KarstensUniversity of Freiburg, Freiburg im Breisgau, GermanyW. KastaunUniversity of Freiburg, Freiburg im Breisgau, GermanyB. KetzerTechnical University of Munich, Munich, Germany
2005en
ABI
Аннотация
We present a determination of the gluon polarization Delta G/G in the nucleon, based on the helicity asymmetry of quasi-real photoproduction events, Q^2<1(GeV/c)^2, with a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarized muon beam scattered on a polarized 6-LiD target. The helicity asymmetry for the selected events is <A_||/D> = 0.002 +- 0.019(stat.) +- 0.003(syst.). From this value, we obtain in a leading-order QCD analysis Delta G/G=0.024 +- 0.089(stat.) +- 0.057(syst.) at x_g = 0.095 and mu^2 =~ 3 (GeV}/c)^2.
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