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We give results for the Upsilon spectrum from lattice QCD using an improvedversion of the NRQCD action for b quarks which includes radiative correctionsto kinetic terms at O(v^4) in the velocity expansion. We also include for thefirst time the effect of up, down, strange and charm quarks in the sea using'second generation' gluon field configurations from the MILC collaboration.Using the {\Upsilon} 2S - 1S splitting to determine the lattice spacing, we areable to obtain the 1P - 1S splitting to 1.4% and the 3S - 1S splitting to 2.4%.Our improved result for M (Upsilon) - M (eta_b) is 70(9) MeV and we predictM(Upsilon) - M(eta_b') = 35(3) MeV. We also calculate pi, K and eta_scorrelators using the Highly Improved Staggered Quark action and perform achiral and continuum extrapolation to give values for M(eta_s) (0.6893(12) GeV)and f_{eta_s} (0.1819(5) GeV) that allow us to tune the strange quark mass aswell as providing an independent and consistent determination of the latticespacing. Combining the NRQCD and HISQ analyses gives mb/ms = 54.7(2.5) and avalue for the heavy quark potential parameter of r_1 = 0.3209(26) fm.

The Upsilon spectrum and the determination of the lattice spacing from lattice QCD including charm quarks in the sea