Measurement of the ttbar production cross section in the fully hadronic decay channel in pp collisions at 7 TeV

Università degli Studi di Firenze

^a e-mail: antonio.tropiano@cern.ch

Abstract

The first measurement of the top quark pair production cross section in the fully hadronic channel at a center-of-mass energy of √s = 7 TeV is presented. The measurement has been performed using an integrated luminosity of 1.09 fb⁻¹, collected with the CMS detector. The reconstruction of the $t\overline{t}$ candidates is performed after a cut-based event selection using a kinematic fit. A data-driven technique is used to estimate the dominant background from QCD multijet production. The cross section is determined from a fit to the top quark mass. The cross section measurement yields σ($t\overline{t}$) = 136 ±20(stat.) ±40(sys.) ±8(lumi.) pb. This result is consistent with an independent measurement in the same channel, with the measurements in other decay channels and with the Standard Model predictions.