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

Abstract

Determination of the top-quark pole mass and strong coupling constant from the t¯t production cross section in pp collisions at vs = 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, mpole t , or the strong coupling constant, aS . With the parton distribution function set NNPDF2.3, a pole mass of 176.7+3.8 -3.4 GeV is obtained when constraining aS at the scale of the Z boson mass, mZ, to the current world average. Alternatively, by constraining mpole t to the latest average from direct mass measurements, a value of aS (mZ) = 0.1151+0.0033-0.0032 is extracted. This is the first determination of aS using events from top-quark production.