Azimuthal asymmetries in unpolarized semi-inclusive deep inelastic scattering at COMPASS

The amplitude of the modulations in the azimuthal angle distribution (azimuthal asymmetries) of hadrons produced in the semi-inclusive deep inelastic scattering on an unpolarized nucleon carries information on the intrinsic transverse momentum of the quark and on the Boer-Mulders parton distribution function. Using the data collected with a 160 GeV muon beam scattering off a liquid-hydrogen target, the COMPASS Collaboration has recently measured the azimuthal asymmetries $A^{\mathrm{cos} φ_h}_{UU}, A^{\mathrm{cos}2φ_h}_{UU}$ and $A^{\mathrm{cos}φ_h}_{LU}$ of charged hadrons. The preliminary results shown here confirm the strong kinematic dependencies observed in previous measurements.