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arXiv · 1704.00488

First measurement of transverse-spin-dependent azimuthal asymmetries in the Drell-Yan process

Aghasyan·R. Akhunzyanov·M. G. Alexeev·G. D. Alexeev·A. Amoroso·V. Andrieux·N. V. Anfimov·V. Anosov·A. Antoshkin·K. Augsten·W. Augustyniak·A. Austregesilo·C. D. R. Azevedo·B. Badelek·F. Balestra·M. Ball·J. Barth·R. Beck·Y. Bedfer·J. Bernhard·K. Bicker·E. R. Bielert·R. Birsa·M. Bodlak·P. Bordalo·F. Bradamante·C. Braun·A. Bressan·M. Buechele·W. -C. Chang·C. Chatterjee·M. Chiosso·I. Choi·S. -U. Chung·A. Cicuttin·M. L. Crespo·S. Dalla Torre·S. S. Dasgupta·S. Dasgupta·O. Yu. Denisov·L. Dhara·S. V. Donskov·N. Doshita·Ch. Dreisbach·W. Duennweber·M. Dziewiecki·A. Efremov·P. D. Eversheim·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·J. Giarra·F. Giordano·I. Gnesi·M. Gorzellik·A. Grasso·M. Grosse Perdekamp·B. Grube·T. Grussenmeyer·A. Guskov·D. Hahne·G. Hamar·D. von Harrach·F. H. Heinsius·R. Heitz·F. Herrmann·N. Horikawa·N. d'Hose·C. -Y. Hsieh·S. Huber·S. Ishimoto·A. Ivanov·Yu. Ivanshin·T. Iwata·V. Jary·R. Joosten·P. Joerg·E. Kabuss·A. Kerbizi·B. Ketzer·G. V. Khaustov·Yu. A. Khokhlov·Yu. Kisselev·F. Klein·J. H. Koivuniemi·V. N. Kolosov·K. Kondo·K. Koenigsmann·I. Konorov·V. F. Konstantinov
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Abstract

The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190 GeV/$c$, $\pi^{-}$ beam and a transversely polarized ammonia target. Three azimuthal asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3 GeV/$c^2$ and 8.5 GeV/$c^2$. The observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of Quantum Chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semi-inclusive deep-inelastic scattering (SIDIS) data. We present two other asymmetries originating from the pion Boer-Mulders TMD PDFs convoluted with either the nucleon transversity or pretzelosity TMD PDFs. These DY results are obtained at a hard scale comparable to that of a recent COMPASS SIDIS measurement and hence allow unique tests of fundamental QCD universality predictions.

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Aghasyan, R. Akhunzyanov, M. G. Alexeev, G. D. Alexeev, A. Amoroso, V. Andrieux, N. V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, A. Austregesilo, C. D. R. Azevedo, B. Badelek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E. R. Bielert, R. Birsa, M. Bodlak, P. Bordalo, F. Bradamante, C. Braun, A. Bressan, M. Buechele, W. -C. Chang, C. Chatterjee, M. Chiosso, I. Choi, S. -U. Chung, A. Cicuttin, M. L. Crespo, S. Dalla Torre, S. S. Dasgupta, S. Dasgupta, O. Yu. Denisov, L. Dhara, S. V. Donskov, N. Doshita, Ch. Dreisbach, W. Duennweber, M. Dziewiecki, A. Efremov, P. D. Eversheim, 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, J. Giarra, F. Giordano, I. Gnesi, M. Gorzellik, A. Grasso, M. Grosse Perdekamp, B. Grube, T. Grussenmeyer, A. Guskov, D. Hahne, G. Hamar, D. von Harrach, F. H. Heinsius, R. Heitz, F. Herrmann, N. Horikawa, N. d'Hose, C. -Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, Yu. Ivanshin, T. Iwata, V. Jary, R. Joosten, P. Joerg, E. Kabuss, A. Kerbizi, B. Ketzer, G. V. Khaustov, Yu. A. Khokhlov, Yu. Kisselev, F. Klein, J. H. Koivuniemi, V. N. Kolosov, K. Kondo, K. Koenigsmann, I. Konorov, V. F. Konstantinov. 2017-04-03. First measurement of transverse-spin-dependent azimuthal asymmetries in the Drell-Yan process. https://doi.org/10.1103/physrevlett.119.112002

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