Azimuthal asymmetries in unpolarized SIDIS can be used to probe the transverse momentum of the quarks inside the nucleon. Furthermore they give access to the so-far unmeasured Boer-Mulders function. We report on the extraction of these asymmetries from the COMPASS data taken with a 160 GeV/c $\mu ^+$ beam impinging on a deuteron target. This asymmetries have been extracted separately for positive and negative hadrons, and the results have been compared with theoretical predictions.
Categories: hep-ex