Production and polarization of $\Upsilon$ mesons in the $k_t$-factorization approach in more detail

In the framework of the $k_t$-factorization approach, the production and polarization of $\Upsilon$ mesons at the Fermilab Tevatron is considered, and a comparision of the calculated double differential distributions and spin alignment parameter $\alpha$ with the D0 experimental data is shown. We argue that measuring the double differential cross section and the polarization of upsilonium states can serve as a crucial test discriminating two competing theoretical approaches to the parton dynamics in QCD.