  The inclusive cross section for top-quark pair production measured by the CMS
experiment in proton-proton collisions at a center-of-mass energy of 7 TeV is
compared to the QCD prediction at next-to-next-to-leading order with various
parton distribution functions to determine the top-quark pole mass, mtpole, or
the strong coupling constant, alphaS. With the parton distribution function set
NNPDF2.3, a pole mass of 176.7 +3.0 -2.8 GeV is obtained when constraining
alphaS at the scale of the Z boson mass, mZ, to the current world average.
Alternatively, by constraining mtpole to the latest average from direct mass
measurements, a value of alphaS(mZ) = 0.1151 +0.0028 -0.0027 is extracted. This
is the first determination of alphaS using events from top-quark production.
