English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present a phenomenological analysis of the $\cos 2 \phi$ asymmetryrecently measured by the COMPASS and HERMES collaborations in unpolarizedsemi-inclusive deep inelastic scattering. In the kinematical regimes exploredby these experiments the asymmetry arises from transverse-spin and intrinsictransverse-momentum effects. We consider the leading-twist contribution,related to the so-called Boer-Mulders transverse-polarization distribution$h_1^{\perp}(x, k_T^2)$, and the twist-4 Cahn contribution, involvingunpolarized transverse-momentum distribution functions. We show that areasonably good fit of the data is achieved with a Boer-Mulders functionconsistent with the main theoretical expectations. Our conclusion is that theCOMPASS and HERMES measurements represent the first experimental evidence ofthe Boer-Mulders effect in SIDIS.

The Boer-Mulders effect in unpolarized SIDIS: an analysis of the COMPASS and HERMES data on the $\cos 2 \phi$ asymmetry