Proceedings of the QCD Evolution Workshop, Jefferson Lab, 14–17 May 2012; Editors: Anatoly Radyushkin and Alexei ProkudinOpen Access

OVERVIEW OF EXPERIMENTAL RESULTS FROM HERMES

MARCO CONTALBRIGO

MARCO CONTALBRIGO

INFN Ferrara, Via Saragat 1 - blocco C, Ferrara, 44121, Italy

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https://doi.org/10.1142/S2010194512009051Cited by:0 (Source: Crossref)

Abstract

The investigation of the partonic degrees of freedom beyond collinear approximation (3D description) has been gained increasing interest in the last decade. At the HERMES experiment, azimuthal asymmetries in hard exclusive reactions and in semi-inclusive deep-inelastic scattering of electrons and positrons off a (polarized) hydrogen and deuterium target have been measured. Such asymmetries provide new insights on crucial aspects of the parton dynamics. By measuring various hadron types in the initial and final states, flavor sensitivity is achieved. Non zero signals are reported for azimuthal asymmetries with respect the transverse target polarization in real-photon exclusive-electroproduction, which are related (still in a model dependent way) to the elusive quark orbital motion. Evidence is reported of the poorly known transversity function and of naive-T-odd transverse-momentum-dependent parton distribution functions related to spin-orbit effects. Evidence of spin-orbit effects in quark fragmentation is also observed, which are opposite in sign for favored and disfavored processes.

Keywords:

PACS: 13.60.-r, 13.88.+e, 14.20.Dh, 14.65.-q

References

V. Barone, A. Drago and P.G. Ratcliffe, Phys. Rep. 359, 1 (2002); V. Barone, F. Bradamante, A. Martin, Prog. Part. Nucl. Phys. 65, 267 (2010) . Google Scholar
R. L. Jaffe and X. Ji, Nucl. Phys. B 375, 527 (1992), DOI: 10.1016/0550-3213(92)90110-W. Crossref, ADS, Google Scholar
A. Bacchetta et al., JHEP 02, 093 (2007); P.J. Mulders and R.D. Tangerman, Nucl. Phys. B 461, 197 (1996); erratumibid. B 484, 538 (1997) . Google Scholar
D. Müller et al., Fortschritte der Physik, 42, 101 (1994); A. V. Radyushkin, Phys. Lett. B 380, 417 (1996); X. Ji, Phys. Rev. D 55, 7114 (1997) . Google Scholar
X. Ji, Phys. Rev. Lett. 78, 610 (1997), DOI: 10.1103/PhysRevLett.78.610. Crossref, ADS, Google Scholar
K. Ackerstaffet al., Nucl. Instrum. Meth. A 417, 230 (1998), DOI: 10.1016/S0168-9002(98)00769-4. Crossref, ADS, Google Scholar
A. V. Belitsky, D. Müller and A. Kirchner, Nucl. Phys. B 629, 323 (2002), DOI: 10.1016/S0550-3213(02)00144-X. Crossref, ADS, Google Scholar
A. Airapetianet al., JHEP 11, 083 (2009). Google Scholar
A. Airapetianet al., Nucl. Phys. B 829, 1 (2010), DOI: 10.1016/j.nuclphysb.2009.12.004. Crossref, ADS, Google Scholar
Hermes Coll., (A. Airapetian et al.), JHEP 06, 019 (2010); Hermes Coll., (A. Airapetian et al.), JHEP 07, 032 (2012) . Google Scholar
A. Airapetianet al., Nucl. Phys. B 842, 265 (2011), DOI: 10.1016/j.nuclphysb.2010.09.010. Crossref, Google Scholar
Hermes Coll., (A. Airapetian et al.), JHEP 06, 066 (2008); Hermes Coll., (A. Airapetian et al.), Phys. Lett B 704, 15 (2011) . Google Scholar
Hermes Coll., (A. Airapetian et al.), to appear in JHEP . Google Scholar
J. C. Collins, Nucl. Phys. B 396, 161 (1993), DOI: 10.1016/0550-3213(93)90262-N. Crossref, ADS, Google Scholar
A. Airapetianet al., Phys. Rev. Lett. 94, 012002 (2005), DOI: 10.1103/PhysRevLett.94.012002. Crossref, Google Scholar
A. Airapetianet al., Phys. Lett. B 693, 11 (2010). Crossref, Google Scholar
Belle Coll., (A. Abe et al.), Phys. Rev. Lett. 96, 232002 (2006); Belle Coll., (R. Seidl et al.), Phys. Rev. D 78 032011 (2008) . Google Scholar
Compass Coll., (M.G. Alekseev et al.), Phys. Lett. B 692 240-246 (2010); Compass Coll., (C. Adolph et al.), e-Print: arXiv:1205.5122; Compass Coll., (C. Adolph et al.), e-Print: arXiv:1205.5121 . Google Scholar
A.V. Efremov, K. Goeke and P. Schweitzer, Phys. Rev. D 73, 094025 (2006); M. Anselmino et al., Phys. Rev. D 75, 054032 (2007); M. Anselmino et al., Nucl. Phys. Proc. Suppl. 191, 98 (2009) . Google Scholar
A. V. Efremov, L. Mankiewicz, and N. A. Tornqvist, Phys. Lett. B 284, 394 (1992); J. C. Collins, S. F. Heppelmann, and G. A. Ladinsky, Nucl. Phys. B 420, 565 (1994); Belle Coll., (A. Vossen et al.), Phys. Rev. Lett. 107, 072004 (2011) . Google Scholar
A. Airapetianet al., Phys. Rev. Lett. 103, 152002 (2007), DOI: 10.1103/PhysRevLett.103.152002. Crossref, Google Scholar
C. Adolphet al., Phys. Lett. B 713, 10 (2012). Crossref, Google Scholar
A. Bacchetta, A. Courtoy and M. Radici, Phys. Rev. Lett. 107, 012001 (2011), DOI: 10.1103/PhysRevLett.107.012001. Crossref, Google Scholar
D. W. Sivers, Phys. Rev. D 41, 83 (1990), DOI: 10.1103/PhysRevD.41.83. Crossref, ADS, Google Scholar
A. Airapetianet al., Phys. Rev. Lett. 103, 152002 (2007), DOI: 10.1103/PhysRevLett.103.152002. Crossref, Google Scholar
W. Vogelsang and F. Yuan, Phys. Rev. D 72, 054028 (2005); M. Anselmino et al., Phys. Rev. D 72, 094007 (2005); J.C. Collins et al., Phys. Rev. D 73, 014021 (2006); M. Anselmino et al., (2010) , arXiv:1012.3565 . Google Scholar
M. G. Alekseevet al., Phys. Lett. B 673, 127 (2009). Crossref, ADS, Google Scholar
D. de Florian, R. Sassot and M. Stratmann, Phys. Rev. D 75, 114010 (2007), DOI: 10.1103/PhysRevD.75.114010. Crossref, ADS, Google Scholar
S. Kretzer, Phys. Rev. D 62, 054001 (2000), DOI: 10.1103/PhysRevD.62.054001. Crossref, Google Scholar
P. Schweitzer, T. Teckentrup and A. Metz, Phys. Rev. D 81, 094019 (2010), DOI: 10.1103/PhysRevD.81.094019. Crossref, Google Scholar
S. M. Aybat and T. C. Rogers, Phys. Rev. D 83, 114042 (2011), DOI: 10.1103/PhysRevD.83.114042. Crossref, Google Scholar
D. Boer and P. J. Mulders, Phys. Rev. D 57, 5780 (1998), DOI: 10.1103/PhysRevD.57.5780. Crossref, ADS, Google Scholar
L. P. Gamberg, G. R. Goldstein and M. Schlegel, Phys. Rev. D 77, 094016 (2008); V. Barone, A. Prokudin and B. Ma, Phys. Rev. D 78, 045022 (2008); B. Zhang, Z. Lu, B. Ma and I. Schmidt, Phys. Rev. D 78, 094035 (2008); V. Barone, A. Prokudin and S. Melis, Phys. Rev. D 81, 114026 (2010) . Google Scholar
Hermes Coll., (A. Airapetian et al.), Phys. Lett. B 562, 182 (2003); Hermes Coll., (A. Airapetian et al.), Phys. Lett. B 622, 14 (2005) . Google Scholar
A. Airapetianet al., Phys. Lett. B 648, 164 (2007). Crossref, ADS, Google Scholar

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OVERVIEW OF EXPERIMENTAL RESULTS FROM HERMES

Abstract

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