Determination of the top-quark pole mass and strong coupling constant from the tt¯ production cross section in pp collisions at √s = 7 TeV

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, m^pole_t , or the strong coupling constant, α_S . With the parton distribution function set NNPDF2.3, a pole mass of 176.7^+3.8_−3.4 GeV is obtained when constraining α_S at the scale of the Z boson mass, m_Z, to the current world average. Alternatively, by constraining m^pole_t to the latest average from direct mass measurements, a value of α_S (m_Z) = 0.1151^+0.0033_−0.0032 is extracted. This is the first determination of α_S using events from top-quark production.