II – Experimental investigation of transverse spin asymmetries in μ-p SIDIS processes: Sivers asymmetries

Adolph, C.; Alekseev, M. G.; Alexakhin, V. Y. u.; Alexandrov, Y. u.; Alexeev, G. D.; Amoroso, Antonio; Antonov, A. A.; Austregesilo, A.; Badełek, B.; Balestra, Ferruccio; Barth, J.; Baum, G.; Bedfer, Y.; Bernhard, J.; Bertini, Raimondo Pietro; Bettinelli, M.; Bicker, K.; Bieling, J.; Birsa, R.; Bisplinghoff, J.; Bordalo, P.; Bradamante, F.; Braun, C.; Bravar, A.; Bressan, A.; Büchele, M.; Burtin, E.; Capozza, L.; Chiosso, Michela; Chung, S. U.; Cicuttin, A.; Crespo, M. L.; Dalla Torre, S.; Das, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Y. u.; Dhara, L.; Donskov, S. V.; Doshita, N.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Elia, C.; Eversheim, P. D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Filin, A.; Finger, M.; Finger, M.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Garfagnini, Raffaello; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Geyer, R.; Giorgi, M.; Gnesi, Ivan; Gobbo, B.; Goertz, S.; Grabmüller, S.; Grasso, Antonino; Grube, B.; Gushterski, R.; Guskov, A.; Guthörl, T.; Haas, F.; von Harrach, D.; Heinsius, F. H.; Herrmann, F.; Heß, C.; Hinterberger, F.; Horikawa, N.; Höppner, C. h.; dʼHose, N.; Huber, S.; Ishimoto, S.; Ivanov, O.; Ivanshin, Y. u.; Iwata, T.; Jahn, R.; Jary, V.; Jasinski, P.; Joosten, R.; Kabuß, E.; Kang, D.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Y. u. A.; Kisselev, Y. u.; Klein, F.; Klimaszewski, K.; Koblitz, S.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Korzenev, A.; Kotzinian, A. M.; Kouznetsov, O.; Krämer, M.; Kroumchtein, Z. V.; Kunne, F.; Kurek, K.; Lauser, L.; Lednev, A. A.; Lehmann, A.; Levorato, S.; Lichtenstadt, J.; Liska, T.; Maggiora, A.; Magnon, A.; Makke, N.; Mallot, G. K.; Mann, A.; Marchand, C.; Martin, A.; Marzec, J.; Matsuda, T.; Meshcheryakov, G.; Meyer, W.; Michigami, T.; Mikhailov, Y. u. V.; Morreale, A.; Mutter, A.; Nagaytsev, A.; Nagel, T.; Negrini, T.; Nerling, F.; Neubert, S.; Neyret, D.; Nikolaenko, V. I.; Nowak, W. D.; Nunes, A. S.; Olshevsky, A. G.; Ostrick, M.; Padee, A.; Panknin, R.; Panzieri, Daniele; Parsamyan, Bakur; Paul, S.; Perevalova, E.; Pesaro, G.; Peshekhonov, D. V.; Piragino, Guido; Platchkov, S.; Pochodzalla, J.; Polak, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Rajotte, J. F.; Ramos, S.; Rapatsky, V.; Reicherz, G.; Richter, A.; Rocco, E.; Rondio, E.; Rossiyskaya, N. S.; Ryabchikov, D. I.; Samoylenko, V. D.; Sandacz, A.; Sapozhnikov, M. G.; Sarkar, S.; Savin, I. A.; Sbrizzai, G.; Schiavon, P.; Schill, C.; Schlüter, T.; Schmidt, K.; Schmitt, L.; Schönning, K.; Schopferer, S.; Schott, M.; Schröder, W.; Shevchenko, O. Y. u.; Silva, L.; Sinha, L.; Sissakian, A. N.; Slunecka, M.; Smirnov, G. I.; Sosio, Stefano; Sozzi, F.; Srnka, A.; Steiger, L.; Stolarski, M.; Sulc, M.; Sulej, R.; Suzuki, H.; Sznajder, P.; Takekawa, S.; Ter Wolbeek, J.; Tessaro, S.; Tessarotto, F.; Tkatchev, L. G.; Uhl, S.; Uman, I.; Vandenbroucke, M.; Virius, M.; Vlassov, N. V.; Wang, L.; Wilfert, M.; Windmolders, R.; Wiślicki, W.; Wollny, H.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zhuravlev, N.; Zvyagin, A.

doi:10.1016/j.physletb.2012.09.056

The COMPASS Collaboration at CERN has measured the transverse spin azimuthal asymmetry of charged hadrons produced in semi-inclusive deep inelastic scattering using a 160 GeV μ+ beam and a transversely polarised NH3 target. The Sivers asymmetry of the proton has been extracted in the Bjorken x range 0.003 < x < 0.7. The new measurements have small statistical and systematic uncertainties of a few percent and confirm with considerably better accuracy the previous COMPASS measurement. The Sivers asymmetry is found to be compatible with zero for negative hadrons and positive for positive hadrons, a clear indication of a spin–orbit coupling of quarks in a transversely polarised proton. As compared to measurements at lower energy, a smaller Sivers asymmetry for positive hadrons is found in the region x > 0.03. The asymmetry is different from zero and positive also in the low x region, where sea-quarks dominate. The kinematic dependence of the asymmetry has also been investigated and results are given for various intervals of hadron and virtual photon fractional energy. In contrast to the case of the Collins asymmetry, the results on the Sivers asymmetry suggest a strong dependence on the four-momentum transfer to the nucleon, in agreement with the most recent calculations.

Titolo:	II – Experimental investigation of transverse spin asymmetries in μ-p SIDIS processes: Sivers asymmetries
Autori Riconosciuti:	C. Adolph M. G. Alekseev V. Y.u. Alexakhin Y.u. Alexandrov G. D. Alexeev AMOROSO, Antonio A. A. Antonov A. Austregesilo B. Badełek BALESTRA, Ferruccio J. Barth G. Baum Y. Bedfer J. Bernhard BERTINI, Raimondo Pietro M. Bettinelli K. Bicker J. Bieling R. Birsa J. Bisplinghoff P. Bordalo F. Bradamante C. Braun A. Bravar A. Bressan M. Büchele E. Burtin L. Capozza CHIOSSO, Michela S. U. Chung A. Cicuttin M. L. Crespo S. Dalla Torre S. Das S. S. Dasgupta S. Dasgupta O. Y.u. Denisov L. Dhara S. V. Donskov N. Doshita V. Duic W. Dünnweber M. Dziewiecki A. Efremov C. Elia P. D. Eversheim W. Eyrich M. Faessler A. Ferrero A. Filin M. Finger M. Finger H. Fischer C. Franco N. du Fresne von Hohenesche J. M. Friedrich V. Frolov GARFAGNINI, Raffaello F. Gautheron O. P. Gavrichtchouk S. Gerassimov R. Geyer M. Giorgi GNESI, IVAN B. Gobbo S. Goertz S. Grabmüller GRASSO, Antonino B. Grube R. Gushterski A. Guskov T. Guthörl F. Haas D. von Harrach F. H. Heinsius F. Herrmann C. Heß F. Hinterberger N. Horikawa C.h. Höppner N. dʼHose S. Huber S. Ishimoto O. Ivanov Y.u. Ivanshin T. Iwata R. Jahn V. Jary P. Jasinski R. Joosten E. Kabuß D. Kang B. Ketzer G. V. Khaustov Y.u. A. Khokhlov Y.u. Kisselev F. Klein K. Klimaszewski S. Koblitz J. H. Koivuniemi V. N. Kolosov K. Kondo K. Königsmann I. Konorov V. F. Konstantinov A. Korzenev A. M. Kotzinian O. Kouznetsov M. Krämer Z. V. Kroumchtein F. Kunne K. Kurek L. Lauser A. A. Lednev A. Lehmann S. Levorato J. Lichtenstadt T. Liska A. Maggiora A. Magnon N. Makke G. K. Mallot A. Mann C. Marchand A. Martin J. Marzec T. Matsuda G. Meshcheryakov W. Meyer T. Michigami Y.u. V. Mikhailov A. Morreale A. Mutter A. Nagaytsev T. Nagel T. Negrini F. Nerling S. Neubert D. Neyret V. I. Nikolaenko W. D. Nowak A. S. Nunes A. G. Olshevsky M. Ostrick A. Padee R. Panknin PANZIERI, Daniele PARSAMYAN, BAKUR S. Paul E. Perevalova G. Pesaro D. V. Peshekhonov PIRAGINO, Guido S. Platchkov J. Pochodzalla J. Polak V. A. Polyakov J. Pretz M. Quaresma C. Quintans J. F. Rajotte S. Ramos V. Rapatsky G. Reicherz A. Richter E. Rocco E. Rondio N. S. Rossiyskaya D. I. Ryabchikov V. D. Samoylenko A. Sandacz M. G. Sapozhnikov S. Sarkar I. A. Savin G. Sbrizzai P. Schiavon C. Schill T. Schlüter K. Schmidt L. Schmitt K. Schönning S. Schopferer M. Schott W. Schröder O. Y.u. Shevchenko L. Silva L. Sinha A. N. Sissakian M. Slunecka G. I. Smirnov SOSIO, Stefano F. Sozzi A. Srnka L. Steiger M. Stolarski M. Sulc R. Sulej H. Suzuki P. Sznajder S. Takekawa J. Ter Wolbeek S. Tessaro F. Tessarotto L. G. Tkatchev S. Uhl I. Uman M. Vandenbroucke M. Virius N. V. Vlassov L. Wang M. Wilfert R. Windmolders W. Wiślicki H. Wollny K. Zaremba M. Zavertyaev E. Zemlyanichkina M. Ziembicki N. Zhuravlev A. Zvyagin mostra contributor esterni nascondi contributor esterni
Autori:	C. Adolph;M.G. Alekseev;V.Yu. Alexakhin;Yu. Alexandrov;G.D. Alexeev;A. Amoroso;A.A. Antonov;A. Austregesilo;B. Badełek;F. Balestra;J. Barth;G. Baum;Y. Bedfer;J. Bernhard;R. Bertini;M. Bettinelli;K. Bicker;J. Bieling;R. Birsa;J. Bisplinghoff;P. Bordalo;F. Bradamante;C. Braun;A. Bravar;A. Bressan;M. Büchele;E. Burtin;L. Capozza;M. Chiosso;S.U. Chung;A. Cicuttin;M.L. Crespo;S. Dalla Torre;S. Das;S.S. Dasgupta;S. Dasgupta;O.Yu. Denisov;L. Dhara;S.V. Donskov;N. Doshita;V. Duic;W. Dünnweber;M. Dziewiecki;A. Efremov;C. Elia;P.D. Eversheim;W. Eyrich;M. Faessler;A. Ferrero;A. Filin;M. Finger;M. Finger;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. Grabmüller;A. Grasso;B. Grube;R. Gushterski;A. Guskov;T. Guthörl;F. Haas;D. von Harrach;F.H. Heinsius;F. Herrmann;C. Heß;F. Hinterberger;N. Horikawa;Ch. Höppner;N. dʼHose;S. Huber;S. Ishimoto;O. Ivanov;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;S. Koblitz;J.H. Koivuniemi;V.N. Kolosov;K. Kondo;K. Königsmann;I. Konorov;V.F. Konstantinov;A. Korzenev;A.M. Kotzinian;O. Kouznetsov;M. Krämer;Z.V. Kroumchtein;F. Kunne;K. Kurek;L. Lauser;A.A. Lednev;A. Lehmann;S. Levorato;J. Lichtenstadt;T. Liska;A. Maggiora;A. Magnon;N. Makke;G.K. Mallot;A. Mann;C. Marchand;A. Martin;J. Marzec;T. Matsuda;G. Meshcheryakov;W. Meyer;T. Michigami;Yu.V. Mikhailov;A. Morreale;A. Mutter;A. Nagaytsev;T. Nagel;T. Negrini;F. Nerling;S. Neubert;D. Neyret;V.I. Nikolaenko;W.-D. Nowak;A.S. Nunes;A.G. Olshevsky;M. Ostrick;A. Padee;R. Panknin;D. Panzieri;B. Parsamyan;S. Paul;E. Perevalova;G. Pesaro;D.V. Peshekhonov;G. Piragino;S. Platchkov;J. Pochodzalla;J. Polak;V.A. Polyakov;J. Pretz;M. Quaresma;C. Quintans;J.-F. Rajotte;S. Ramos;V. Rapatsky;G. Reicherz;A. Richter;E. Rocco;E. Rondio;N.S. Rossiyskaya;D.I. Ryabchikov;V.D. Samoylenko;A. Sandacz;M.G. Sapozhnikov;S. Sarkar;I.A. Savin;G. Sbrizzai;P. Schiavon;C. Schill;T. Schlüter;K. Schmidt;L. Schmitt;K. Schönning;S. Schopferer;M. Schott;W. Schröder;O.Yu. Shevchenko;L. Silva;L. Sinha;A.N. Sissakian;M. Slunecka;G.I. Smirnov;S. Sosio;F. Sozzi;A. Srnka;L. Steiger;M. Stolarski;M. Sulc;R. Sulej;H. Suzuki;P. Sznajder;S. Takekawa;J. Ter Wolbeek;S. Tessaro;F. Tessarotto;L.G. Tkatchev;S. Uhl;I. Uman;M. Vandenbroucke;M. Virius;N.V. Vlassov;L. Wang;M. Wilfert;R. Windmolders;W. Wiślicki;H. Wollny;K. Zaremba;M. Zavertyaev;E. Zemlyanichkina;M. Ziembicki;N. Zhuravlev;A. Zvyagin
Data di pubblicazione:	2012
Abstract:	The COMPASS Collaboration at CERN has measured the transverse spin azimuthal asymmetry of charged hadrons produced in semi-inclusive deep inelastic scattering using a 160 GeV μ+ beam and a transversely polarised NH3 target. The Sivers asymmetry of the proton has been extracted in the Bjorken x range 0.003 < x < 0.7. The new measurements have small statistical and systematic uncertainties of a few percent and confirm with considerably better accuracy the previous COMPASS measurement. The Sivers asymmetry is found to be compatible with zero for negative hadrons and positive for positive hadrons, a clear indication of a spin–orbit coupling of quarks in a transversely polarised proton. As compared to measurements at lower energy, a smaller Sivers asymmetry for positive hadrons is found in the region x > 0.03. The asymmetry is different from zero and positive also in the low x region, where sea-quarks dominate. The kinematic dependence of the asymmetry has also been investigated and results are given for various intervals of hadron and virtual photon fractional energy. In contrast to the case of the Collins asymmetry, the results on the Sivers asymmetry suggest a strong dependence on the four-momentum transfer to the nucleon, in agreement with the most recent calculations.
Volume:	717
Pagina iniziale:	383
Pagina finale:	389
Digital Object Identifier (DOI):	10.1016/j.physletb.2012.09.056
Parole Chiave:	COMPASS; SIDIS; spin asymmetries; Sivers asymmetries
Rivista:	PHYSICS LETTERS. SECTION B
Appare nelle tipologie:	03A-Articolo su Rivista

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