NLO QCD predictions for $\Delta G/G$ from open charm $D^{0}$ production at COMPASS

One of the main goals of the COMPASS experiment is the measurement of the gluon contribution to the nucleon spin. Among the processes studied by COMPASS, the open-charm $D^{0}$ meson production is the cleanest channel for the gluon polarisation estimation. The gluon polarisation was estimated through the relation between the measured asymmetry for charmed mesons and the analyzing power (asymmetry at the partonic level) from the photon-gluon fusion process, corresponds to a LO QCD approximation. The significant improvement of the statistical precision is also reported in this conference by COMPASS. The NLO QCD corrections to the partonic cross sections (unpolarized and polarized) should be included in the analysis since these higher order contributions are considered to be non-negligible in COMPASS kinematical domain. The treatment of the data in NLO QCD approximation in the COMPASS open-charm analysis is presented. The NLO QCD prediction for the gluon polarisation based on asymmetries for $D^{0}$ meson production published by COMPASS, is discussed.