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arXiv · 1509.03526

Longitudinal double spin asymmetries in single hadron quasi-real photoproduction at high $p_T$

COMPASS Collaboration·C. Adolph·R. Akhunzyanov·M. G. Alexeev·G. D. Alexeev·A. Amoroso·V. Andrieux·V. Anosov·W. Augustyniak·A. Austregesilo·C. D. R. Azevedo·B. Badełek·F. Balestra·J. Barth·R. Beck·Y. Bedfer·J. Bernhard·K. Bicker·E. R. Bielert·R. Birsa·J. Bisplinghoff·M. Bodlak·M. Boer·P. Bordalo·F. Bradamante·C. Braun·A. Bressan·M. Büchele·E. Burtin·W. -C. Chang·M. Chiosso·I. Choi·S. -U. Chung·A. Cicuttin·M. L. Crespo·Q. Curiel·S. Dalla Torre·S. S. Dasgupta·S. Dasgupta·O. Yu. Denisov·L. Dhara·S. V. Donskov·N. Doshita·V. Duic·W. Dünnweber·M. Dziewiecki·A. Efremov·P. D. Eversheim·W. Eyrich·M. Faessler·A. Ferrero·M. Finger·M. Finger jr.·H. Fischer·C. Franco·N. du Fresne von Hohenesche·J. M. Friedrich·V. Frolov·E. Fuchey·F. Gautheron·O. P. Gavrichtchouk·S. Gerassimov·F. Giordano·I. Gnesi·M. Gorzellik·S. Grabmüller·A. Grasso·M. Grosse Perdekamp·B. Grube·T. Grussenmeyer·A. Guskov·F. Haas·D. Hahne·D. von Harrach·R. Hashimoto·F. H. Heinsius·F. Herrmann·F. Hinterberger·N. Horikawa·N. d'Hose·C. -Y. Hsieh·S. Huber·S. Ishimoto·A. Ivanov·Yu. Ivanshin·T. Iwata·R. Jahn·V. Jary·R. Joosten·P. Jörg·E. Kabuß·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

We measured the longitudinal double spin asymmetries $A_{LL}$ for single hadron muo-production off protons and deuterons at photon virtuality $Q^2$ < 1(GeV/$\it c$)$^2$ for transverse hadron momenta $p_T$ in the range 0.7 GeV/$\it c$ to 4 GeV/$\it c$ . They were determined using COMPASS data taken with a polarised muon beam of 160 GeV/$\it c$ or 200 GeV/$\it c$ impinging on polarised $\mathrm{{}^6LiD}$ or $\mathrm{NH_3}$ targets. The experimental asymmetries are compared to next-to-leading order pQCD calculations, and are sensitive to the gluon polarisation $\Delta G$ inside the nucleon in the range of the nucleon momentum fraction carried by gluons $0.05 < x_g < 0.2$.

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COMPASS Collaboration, C. Adolph, R. Akhunzyanov, M. G. Alexeev, G. D. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, W. Augustyniak, A. Austregesilo, C. D. R. Azevedo, B. Badełek, F. Balestra, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E. R. Bielert, R. Birsa, J. Bisplinghoff, M. Bodlak, M. Boer, P. Bordalo, F. Bradamante, C. Braun, A. Bressan, M. Büchele, E. Burtin, W. -C. Chang, M. Chiosso, I. Choi, S. -U. Chung, A. Cicuttin, M. L. Crespo, Q. Curiel, S. Dalla Torre, S. S. Dasgupta, S. Dasgupta, O. Yu. Denisov, L. Dhara, S. V. Donskov, N. Doshita, V. Duic, W. Dünnweber, M. Dziewiecki, A. Efremov, P. D. Eversheim, W. Eyrich, M. Faessler, A. Ferrero, M. Finger, M. Finger jr., H. Fischer, C. Franco, N. du Fresne von Hohenesche, J. M. Friedrich, V. Frolov, E. Fuchey, F. Gautheron, O. P. Gavrichtchouk, S. Gerassimov, F. Giordano, I. Gnesi, M. Gorzellik, S. Grabmüller, A. Grasso, M. Grosse Perdekamp, B. Grube, T. Grussenmeyer, A. Guskov, F. Haas, D. Hahne, D. von Harrach, R. Hashimoto, F. H. Heinsius, F. Herrmann, F. Hinterberger, N. Horikawa, N. d'Hose, C. -Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, Yu. Ivanshin, T. Iwata, R. Jahn, V. Jary, R. Joosten, P. Jörg, E. Kabuß, B. Ketzer, G. V. Khaustov, Yu. A. Khokhlov, Yu. Kisselev, F. Klein, K. Klimaszewski, J. H. Koivuniemi, V. N. Kolosov, K. Kondo. 2015-09-11. Longitudinal double spin asymmetries in single hadron quasi-real photoproduction at high $p_T$. https://arxiv.org/abs/1509.03526

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