Boer-Mulders effect in unpolarized SIDIS: An analysis of the COMPASS and HERMES data on the cos 2φ asymmetry

Vincenzo Barone, Stefano Melis, Alexei Prokudin

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We present a phenomenological analysis of the cos 2φ asymmetry recently measured by the COMPASS and HERMES collaborations in unpolarized semi-inclusive deep inelastic scattering. In the kinematical regimes explored by these experiments the asymmetry arises from transverse-spin and intrinsic transverse-momentum effects. We consider the leading-twist contribution, related to the so-called Boer-Mulders transverse-polarization distribution h1 (x,kT2), and the twist-4 Cahn contribution, involving unpolarized transverse-momentum distribution functions. We show that a reasonably good fit of the preliminary data sets from COMPASS and HERMES is achieved with a Boer-Mulders function consistent with the main theoretical expectations. Our conclusion is that the COMPASS and HERMES measurements represent the first experimental evidence of the Boer-Mulders effect in SIDIS.

Original languageEnglish (US)
Article number114026
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number11
Publication statusPublished - Jun 17 2010


All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)

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