Azimuthal asymmetries in production of charged hadrons by high energy muons on polarized deuterium targets

Abstract

Search for azimuthal asymmetries in semi-inclusive production of charged hadrons by 160 GeV muons on the longitudinally polarized deuterium target, has been performed using the 2002- 2004 COMPASS data. The observed asymmetries integrated over the kinematical variables do not depend on the azimuthal angle of produced hadrons and are consistent with the ratio $g_1^d(x)/f_1^d(x)$. The asymmetries are parameterized taking into account possible contributions from different parton distribution functions and parton fragmentation functions depending on the transverse spin of quarks.They can be modulated (either/or/and) with $\sin(\phi), \sin(2\phi), \sin(3\phi)$ and $\cos(\phi)$. The $x$-, $z$- and $p_h^T$-dependencies of these amplitudes are studied.