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

Abstract

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