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arXiv · 1310.1454

Transverse target spin asymmetries in exclusive $\rho^0$ muoproduction

C. Adolph·M. G. Alekseev·V. Yu. Alexakhin·Yu. Alexandrov·G. D. Alexeev·A. Amoroso·V. Andrieux·A. Austregesilo·B. Badellek·F. Balestra·J. Barth·G. Baum·Y. Bedfer·A. Berlin·J. Bernhard·R. Bertini·K. Bicker·J. Bieling·R. Birsa·J. Bisplinghoff·M. Boer·P. Bordalo·F. Bradamante·C. Braun·A. Bravar·A. Bressan·M. Buechele·E. Burtin·L. Capozza·M. Chiosso·S. U. Chung·A. Cicuttin·M. L. Crespo·S. Dalla Torre·S. S. Dasgupta·S. Dasgupta·O. Yu. Denisov·S. V. Donskov·N. Doshita·V. Duic·W. Duennweber·M. Dziewiecki·A. Efremov·C. Elia·P. D. Eversheim·W. Eyrich·M. Faessler·A. Ferrero·A. Filin·M. Finger·M. Finger jr.·H. Fischer·C. Franco·N. du Fresne von Hohenesche·J. M. Friedrich·V. Frolov·R. Garfagnini·F. Gautheron·O. P. Gavrichtchouk·S. Gerassimov·R. Geyer·M. Giorgi·I. Gnesi·B. Gobbo·S. Goertz·S. Grabmueller·A. Grasso·B. Grube·R. Gushterski·A. Guskov·T. Guthoerl·F. Haas·D. von Harrach·D. Hahne·F. H. Heinsius·F. Herrmann·C. Hess·F. Hinterberger·Ch. Hoeppner·N. Horikawa·N. d'Hose·S. Huber·S. Ishimoto·Yu. Ivanshin·T. Iwata·R. Jahn·V. Jary·P. Jasinski·R. Joosten·E. Kabuss·D. Kang·B. Ketzer·G. V. Khaustov·Yu. A. Khokhlov·Yu. Kisselev·F. Klein·K. Klimaszewski·J. H. Koivuniemi·V. N. Kolosov·K. Kondo
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Abstract

Exclusive production of $\rho^0$ mesons was studied at the COMPASS experiment by scattering 160 GeV/$c$ muons off transversely polarised protons. Five single-spin and three double-spin azimuthal asymmetries were measured as a function of $Q^2$, $x_{Bj}$, or $p_{T}^{2}$. The $\sin \phi_S$ asymmetry is found to be $-0.019 \pm 0.008(stat.) \pm 0.003(syst.)$. All other asymmetries are also found to be of small magnitude and consistent with zero within experimental uncertainties. Very recent calculations using a GPD-based model agree well with the present results. The data is interpreted as evidence for the existence of chiral-odd, transverse generalized parton distributions.

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C. Adolph, M. G. Alekseev, V. Yu. Alexakhin, Yu. Alexandrov, G. D. Alexeev, A. Amoroso, V. Andrieux, A. Austregesilo, B. Badellek, F. Balestra, J. Barth, G. Baum, Y. Bedfer, A. Berlin, J. Bernhard, R. Bertini, K. Bicker, J. Bieling, R. Birsa, J. Bisplinghoff, M. Boer, P. Bordalo, F. Bradamante, C. Braun, A. Bravar, A. Bressan, M. Buechele, E. Burtin, L. Capozza, M. Chiosso, S. U. Chung, A. Cicuttin, M. L. Crespo, S. Dalla Torre, S. S. Dasgupta, S. Dasgupta, O. Yu. Denisov, S. V. Donskov, N. Doshita, V. Duic, W. Duennweber, M. Dziewiecki, A. Efremov, C. Elia, P. D. Eversheim, W. Eyrich, M. Faessler, A. Ferrero, A. Filin, M. Finger, M. Finger jr., H. Fischer, C. Franco, N. du Fresne von Hohenesche, J. M. Friedrich, V. Frolov, R. Garfagnini, F. Gautheron, O. P. Gavrichtchouk, S. Gerassimov, R. Geyer, M. Giorgi, I. Gnesi, B. Gobbo, S. Goertz, S. Grabmueller, A. Grasso, B. Grube, R. Gushterski, A. Guskov, T. Guthoerl, F. Haas, D. von Harrach, D. Hahne, F. H. Heinsius, F. Herrmann, C. Hess, F. Hinterberger, Ch. Hoeppner, N. Horikawa, N. d'Hose, S. Huber, S. Ishimoto, Yu. Ivanshin, T. Iwata, R. Jahn, V. Jary, P. Jasinski, R. Joosten, E. Kabuss, D. Kang, B. Ketzer, G. V. Khaustov, Yu. A. Khokhlov, Yu. Kisselev, F. Klein, K. Klimaszewski, J. H. Koivuniemi, V. N. Kolosov, K. Kondo. 2013-10-05. Transverse target spin asymmetries in exclusive $\rho^0$ muoproduction. https://doi.org/10.1016/j.physletb.2014.02.005

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