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

M. Aghasyan , R. Akhunzyanov , M.G. Alexeev , G.D. Alexeev , A. Amoroso , V. Andrieux (1) , N.V. Anfimov , V. Anosov , A. Antoshkin , K. Augsten , W. Augustyniak , A. Austregesilo , C.D.R. Azevedo , B. Badełek , F. Balestra , M. Ball , J. Barth , R. Beck , Y. Bedfer (1) , J. Bernhard , K. Bicker , E.R. Bielert , R. Birsa , M. Bodlak , P. Bordalo , F. Bradamante , A. Bressan , M. Büchele , W.-C. Chang , C. Chatterjee , M. Chiosso , I. Choi , S.-U. Chung , A. Cicuttin , M.L. Crespo , S. Dalla Torre , S.S. Dasgupta , O.Yu. Denisov , L. Dhara , S.V. Donskov , N. Doshita , Ch. Dreisbach , W. Dünnweber , M. Dziewiecki , A. Efremov , P.D. Eversheim , M. Faessler , A. Ferrero (1) , M. Finger , H. Fischer , C. Franco , N. Du Fresne von Hohenesche , J.M. Friedrich , V. Frolov , E. Fuchey (1, 2) , 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 (1) , C.-Y. Hsieh , S. Huber , S. Ishimoto , A. Ivanov , Yu. Ivanshin , T. Iwata , V. Jary , R. Joosten , P. Jörg , 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. Königsmann , I. Konorov , V.F. Konstantinov , A.M. Kotzinian , O.M. Kouznetsov , Z. Kral , M. Krämer , P. Kremser , F. Krinner , Z.V. Kroumchtein , Y. Kulinich , F. Kunne (1) , K. Kurek , R.P. Kurjata , A. Kveton , A.A. Lednev , M. Levillain (1) , S. Levorato , Y.-S. Lian , J. Lichtenstadt , R. Longo , A. Maggiora , A. Magnon , N. Makins , N. Makke , G.K. Mallot , B. Marianski , A. Martin , J. Marzec , J. Matoušek , H. Matsuda , T. Matsuda , G.V. Meshcheryakov , M. Meyer (1) , W. Meyer , Yu.V. Mikhailov , M. Mikhasenko , E. Mitrofanov , N. Mitrofanov , Y. Miyachi , A. Nagaytsev , F. Nerling , D. Neyret (1) , J. Nový , W.-D. Nowak , G. Nukazuka , A.S. Nunes , A.G. Olshevsky , I. Orlov , M. Ostrick , D. Panzieri , B. Parsamyan , S. Paul , J.-C. Peng , F. Pereira , M. Pešek , D.V. Peshekhonov , N. Pierre (1) , S. Platchkov (1) , J. Pochodzalla , V.A. Polyakov , J. Pretz , M. Quaresma , C. Quintans , S. Ramos , C. Regali , G. Reicherz , C. Riedl , N.S. Rogacheva , M. Roskot , D.I. Ryabchikov , A. Rybnikov , A. Rychter , R. Salac , V.D. Samoylenko , A. Sandacz , C. Santos , S. Sarkar , I.A. Savin , T. Sawada , G. Sbrizzai , P. Schiavon , K. Schmidt , H. Schmieden , K. Schönning , E. Seder (1) , A. Selyunin , L. Silva , L. Sinha , S. Sirtl , M. Slunecka , J. Smolik , A. Srnka , D. Steffen , M. Stolarski , O. Subrt , M. Sulc , H. Suzuki , A. Szabelski , T. Szameitat , P. Sznajder , M. Tasevsky , S. Tessaro , F. Tessarotto , A. Thiel , J. Tomsa , F. Tosello , V. Tskhay , S. Uhl , A. Vauth , J. Veloso , M. Virius , J. Vondra , S. Wallner , T. Weisrock , M. Wilfert , J. ter Wolbeek , K. Zaremba , P. Zavada , M. Zavertyaev , E. Zemlyanichkina , N. Zhuravlev , M. Ziembicki

1 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
2 CEA - Commissariat à l'énergie atomique et aux énergies alternatives

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 π- 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/c2 and 8.5  GeV/c2. Within the experimental uncertainties, 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. A recent COMPASS SIDIS measurement was obtained at a hard scale comparable to that of these DY results. This opens the way for possible tests of fundamental QCD universality predictions.

Mots clés: pi- nucleus: scattering; polarized target: transverse; angular distribution: asymmetry; deep inelastic scattering: semi-inclusive reaction; parton: distribution function; quantum chromodynamics; Drell-Yan process; spin: asymmetry; Sivers function; mass spectrum: (muon+ muon-); transverse momentum dependence; universality; transversity; CERN SPS; nucleon; COMPASS; dimuon: mass spectrum; experimental results; 190 GeV/c

Domaines: Physique des Hautes Energies - Expérience [hep-ex]; Physique des Hautes Energies - Phénoménologie [hep-ph]

M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, et al.. First measurement of transverse-spin-dependent azimuthal asymmetries in the Drell-Yan process. Physical Review Letters, 2017, 119 (11), pp.112002. ⟨10.1103/PhysRevLett.119.112002⟩. ⟨hal-01645533⟩