2013 Theses Doctoral

A Measurement of the Jet Multiplicity in Di-lepton Final States of ttbar Events

Urbaniec, Dustin Henry

A measurement of the jet multiplicity in di-leptonically decaying ttbar events (i.e. ttbar → (ee, μμ, eμ) + missing transverse momentum + jets) is presented, using 4.66 fb -1 of data collected from √ s = 7 TeV pp collisions at the CERN Large Hadron Collider. In order to mitigate the effects of systematic uncertainties associated with jet energy measurements, a measurement of the ratio of the number of di-lepton ttbar events with N + 2 jets to Z → ℓ ℓ + N jet events is also determined. The results are unfolded for detector effects and compared to the particle-level predictions of several Monte Carlo generators, showing generally good agreement.