Study of the J/psi production in the muon decay channel in the ATLAS experiment

We present a preliminary measurement of inclusive differential production cross-section and polarization of the J/ψ meson in pp collisions at center of mass energy of 7 TeV with the ATLAS experiment. The differential cross-section is measured as a function of the J/psi transverse momentum for a rapidity range |y|<2.5. This measurement has been performed under different polarization hypothesis in order to estimate the spin-alignment uncertainty due to the unknown polarization state of the produced J/psi. A complete polarization measurement is performed in the Helicity and Collins-Soper frames with two different fitting methods for the angular distribution of the decayed muons. The statistic is not enough to have a conclusive result, but this preliminary results allows to demonstrate the goodness of our analysis chain.