We analyze Tevatron data of bottomonium hadroproduction in the framework of
the colour-octet model (COM) implemented in the event generator PYTHIA [1]
using CTEQ4L PDF taking into account initial-state radiation of gluons and
Altarelli-Parisi evolution of final-state gluons. We obtain new values for
the colour-octet matrix elements (Me's) relevant to this production proces
s for the Y (nS) family (n=1,2,3), finding that S-1(0)(8) +(3) P-J((8)) con
tributions are not needed in the fit. We show the different contributions t
o Y (1S) production at Tevatron for P-T > 8 GeV, comparing them with CDF da
ta. Remarkably we find a quite small contribution (compatible with zero! fr
om feeddown of chi (bJ) states produced through the colour-octet mechanism:
Y (1S) indirect production via chi (bJ) decays should be mainly ascribed t
o the colour-singlet model. Finally we extrapolate to LHC energies to predi
ct Y (nS) production rates.