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Semi-inclusive π<sup>0</sup> target and beam-target asymmetries from 6 GeV electron scattering with CLAS
Journal
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Date Issued
2018-07-10
Author(s)
Jawalkar, S.
Koirala, S.
Avakian, H.
Bosted, P.
Griffioen, K. A.
Keith, C.
Kuhn, S. E.
Adhikari, K. P.
Adhikari, S.
Adikaram, D.
Akbar, Z.
Amaryan, M. J.
Anefalos Pereira, S.
Ball, J.
Baltzell, N. A.
Battaglieri, M.
Batourine, V.
Bedlinskiy, I.
Biselli, A. S.
Boiarinov, S.
Briscoe, W. J.
Brock, J.
Bültmann, S.
Burkert, V. D.
Cao, Frank Thanh
Carlin, C.
Carman, D. S.
Celentano, A.
Charles, G.
Chetry, T.
Ciullo, G.
Clark, L.
Colaneri, L.
Cole, P. L.
Contalbrigo, M.
Cortes, O.
Crede, V.
D'Angelo, A.
Dashyan, N.
De Vita, R.
De Sanctis, E.
Defurne, M.
Deur, A.
Djalali, C.
Ddoge, G.
Dupre, R.
Egiyan, H.
El Fassi, L.
Elouadrhiri, L.
Eugenio, P.
Fedotov, G.
Fegan, S.
Fersch, R.
Filippi, A.
Fleming, J. A.
Forest, T. A.
Fradi, A.
Garçon, M.
Ghandilyan, Y.
Gilfoyle, G. P.
Giovanetti, K. L.
Girod, F. X.
Gleason, C.
Gohn, W.
Golovatch, E.
Gothe, R. W.
Guidal, M.
Guler, N.
Guo, L.
Hanretty, C.
Harrison, N.
Hattawy, M.
Heddle, D.
Hicks, K.
Hollis, G.
Holtrop, M.
Hughes, S. M.
Ilieva, Y.
Ireland, D. G.
Ishkhanov, B. S.
Isupov, E. L.
Jenkins, D.
Jiang, H.
Joo, K.
Joosten, S.
Keller, D.
Khachatryan, G.
Khachatryan, M.
Khandaker, M.
Kim, A.
Kim, W.
Klein, A.
Klein, F. J.
Kubarovsky, V.
Lanza, L.
Abstract
We present precision measurements of the target and beam-target spin asymmetries from neutral pion
electroproduction in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer
(CLAS) at Jefferson Lab. We scattered 6-GeV, longitudinally polarized electrons off longitudinally polarized
protons in a cryogenic 14NH3 target, and extracted double and single target spin asymmetries for
ep → e
π0 X in multidimensional bins in four-momentum transfer (1.0 < Q 2 < 3.2 GeV2), Bjorken-x
(0.12 < x < 0.48), hadron energy fraction (0.4 < z < 0.7), transverse pion momentum (0 < PT < 1.0 GeV),
and azimuthal angle φh between the lepton scattering and hadron production planes. We extracted
asymmetries as a function of both x and PT , which provide access to transverse-momentum distributions
of longitudinally polarized quarks. The double spin asymmetries depend weakly on PT . The sin 2φh
moments are zero within uncertainties, which is consistent with the expected suppression of the
Collins fragmentation function. The observed sinφh moments suggest that quark gluon correlations are
significant at large x.
electroproduction in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer
(CLAS) at Jefferson Lab. We scattered 6-GeV, longitudinally polarized electrons off longitudinally polarized
protons in a cryogenic 14NH3 target, and extracted double and single target spin asymmetries for
ep → e
π0 X in multidimensional bins in four-momentum transfer (1.0 < Q 2 < 3.2 GeV2), Bjorken-x
(0.12 < x < 0.48), hadron energy fraction (0.4 < z < 0.7), transverse pion momentum (0 < PT < 1.0 GeV),
and azimuthal angle φh between the lepton scattering and hadron production planes. We extracted
asymmetries as a function of both x and PT , which provide access to transverse-momentum distributions
of longitudinally polarized quarks. The double spin asymmetries depend weakly on PT . The sin 2φh
moments are zero within uncertainties, which is consistent with the expected suppression of the
Collins fragmentation function. The observed sinφh moments suggest that quark gluon correlations are
significant at large x.
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