Determination of the top-quark pole mass and strong coupling constant from the ttbar production cross section in pp collisions at sqrt(s) = 7 TeV

CMS Collaboration [UCL] Basegmez, Suzan [UCL] Bruno, Giacomo [UCL] Castello, Roberto [UCL] Caudron, Adrien [UCL] Ceard, Ludivine [UCL] Delaere, Christophe [UCL] Du Pree, Tristan [UCL] Favart, Denis [UCL] Forthomme, Laurent [UCL] Hollar, Jonathan [UCL] Jez, Pavel [UCL] Lemaitre, Vincent [UCL] Liao, Junhui [UCL] Militaru, Otilia [UCL] Nuttens, Claude [UCL] Pagano, Davide [UCL] Pin, Arnaud [UCL] Piotrzkowski, Krzysztof [UCL] Selvaggi, Michele [UCL] Vizan Garcia, Jesús Manuel [UCL] Quertenmont, Loic [UCL]

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$^{+3.0}_{-2.8}$ GeV is obtained when constraining $\alpha_S$ at the scale of the Z boson mass, $m_Z$, 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$^{+0.0028}_{-0.0027}$ is extracted. This is the first determination of $\alpha_S$ using events from top-quark production.