  Using 1.8 fb-1 of pp collisions at a center-of-mass energy of 7 TeV recorded
by the ATLAS detector at the Large Hadron Collider, we present measurements of
the production cross sections of Upsilon(1S,2S,3S) mesons. Upsilon mesons are
reconstructed using the di-muon decay mode. Total production cross sections for
p_T<70 GeV and in the rapidity interval |Upsilon|<2.25 are measured to be
8.01+-0.02+-0.36+-0.31 nb, 2.05+-0.01+-0.12+-0.08 nb, 0.92+-0.01+-0.07+-0.04 nb
respectively, with uncertainties separated into statistical, systematic, and
luminosity measurement effects. In addition, differential cross section times
di-muon branching fractions for Upsilon(1S), Upsilon(2S), and Upsilon(3S) as a
function of Upsilon transverse momentum p_T and rapidity are presented. These
cross sections are obtained assuming unpolarized production. If the production
polarization is fully transverse or longitudinal with no azimuthal dependence
in the helicity frame the cross section may vary by approximately +-20%. If a
non-trivial azimuthal dependence is considered, integrated cross sections may
be significantly enhanced by a factor of two or more. We compare our results to
several theoretical models of Upsilon meson production, finding that none
provide an accurate description of our data over the full range of Upsilon
transverse momenta accessible with this dataset.
