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

TL;DR

This paper reports the first measurement of the top quark pair production cross section in the fully hadronic decay channel at 7 TeV using CMS data, employing a data-driven background estimate and a kinematic fit.

Contribution

It presents the first measurement of the ttbar cross section in the fully hadronic channel at 7 TeV, utilizing a novel data-driven background estimation method and a kinematic fit for candidate reconstruction.

Findings

Measured cross section: 136 ± 20 (stat.) ± 40 (sys.) ± 8 (lumi.) pb

Result consistent with Standard Model predictions

Agreement with previous measurements in other channels

Abstract

The first measurement of the top quark pair production cross section in the fully hadronic channel at a center-of-mass energy of $\sqrt s = 7$ 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 $t\bar t$ 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 $\sigma(t\bar t)=136 \pm 20 (stat.) \pm 40 (sys.) \pm 8 (lumi.)$ 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.