Normalized double-differential cross sections for top quark pair (tt) production are measured in pp collisions at a centre-of-mass energy of 8TeV with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7fb−1. The measurement is performed in the dilepton e+- mu tau final state. The tt cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and tt¯ system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions are used. The inclusion of the measured tt¯ cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution.
Measurement of double-differential cross sections for top quark pair production in pp collisions at sqrt(s)=8TeV and impact on parton distribution functions
Amapane, N.;Argiro, S.;Bellan, R.;Costa, M.;Covarelli, R.;Kiani, B.;Migliore, E.;Monaco, V.;Monteil, E.;Obertino, M. M.;Pacher, L.;Pinna Angioni, G. L.;Ravera, F.;Romero, A.;Sacchi, R.;Sola, V.;Solano, A.;
2017-01-01
Abstract
Normalized double-differential cross sections for top quark pair (tt) production are measured in pp collisions at a centre-of-mass energy of 8TeV with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7fb−1. The measurement is performed in the dilepton e+- mu tau final state. The tt cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and tt¯ system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions are used. The inclusion of the measured tt¯ cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution.| File | Dimensione | Formato | |
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