Measurement of the spin asymmetry in the photoproduction of pairs of high- p(T) hadrons at HERMES |
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Authors: | McIlhany McKeown Meissner Menden Metz Meyners Mikloukho Miller Miller Milner Most Muccifora Naryshkin Nathan Neunreither Niczyporuk Nowak O'Neill Openshaw Ouyang Owen Pate Potashov Potterveld Rakness Redwine |
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Institution: | Yerevan Physics Institute, 375036, Yerevan, Armenia. |
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Abstract: | We present a measurement of the longitudinal spin asymmetry A(||) in photoproduction of pairs of hadrons with high transverse momentum p(T). Data were accumulated by the HERMES experiment using a 27.5 GeV polarized positron beam and a polarized hydrogen target internal to the HERA storage ring. For h(+)h(-) pairs with p(h(1))(T)>1.5 GeV/c and p(h(2))(T)>1.0 GeV/c, the measured asymmetry is A(||) = -0. 28+/-0.12(stat)+/-0.02(syst). This negative value is in contrast to the positive asymmetries typically measured in deep inelastic scattering from protons, and is interpreted to arise from a positive gluon polarization. |
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