Measurement of the top quark mass in the lepton+jets final state with the matrix element method

We present a measurement of the top quarkmass with the Matrix Element method in the lepton+jets final state. As the energy scale for calorimeterjets represents the dominant source of systematicuncertainty, the Matrix Element likelihood is extended by an additional parameter, which is defined as a global multiplicative factor applied to the standard energy scale. The top quarkmass is obtained from a fit that yields the combined statistical and systematicjet energy scale uncertainty.