Matrix Element Analysis in the Dilepton Channel

A. Kovalev¹, B. Jayatilaka², M. Tecchio², D. Whiteson¹, D. Gerdes², H. H. Williams¹

¹ University of Pennsylvania
² University of Michigan

CDF Collaboration

E-mail authors

We present a measurement of the top quark mass in the dilepton channel using a technique in which we form a posterior probability for the mass as a product of the per-event differential cross-section for leading order top quark pair production. The calculation of the differential cross section for processes which produce background events are used to reduce the impact of background events in the sample.

In 340 pb^-1 of Run II data, we expect a statistical uncertainty of 9.4 GeV if M_top=178.0 GeV/c² (7.8 GeV/c² if M_top=165.0 GeV/c²) and a systematic uncertainty of 3.6 GeV/c². We measure M_top = 165.3 ± 6.3 (stat.) ± 3.6 (syst.) GeV/c²

Documentation

A note describing this analysis can be found here.
Internal page for CDF collaborators

Tables and Plots

Description	jpg	pdf/eps
Final posterior probability density as a function of top pole mass for the 33 dilepton candidate events in data.		pdf/eps
Final posterior probability density as a function of top pole mass for the 33 dilepton candidate events in data with an overlaid gaussian fit.		pdf/eps
Expected distribution of errors from MC (M_t=165 GeV/c²) and measured error in data. 17% of pseudo-experiments had an error lower than that measured in data.		pdf/eps
Response for pseudo-experiments of signal and background events.		pdf/eps
Residual, pull mean, and pull width for varying top mass MC samples before scaling of statistical error		pdf/eps
Residual, pull mean, and pull width for varying top mass MC samples after scaling of statistical error		pdf/eps
Table of systematic errors.		pdf
Evaluation of the ttbar probability (evaluated at M_top=165 GeV/c²) for simulated events, scaled by expected contribution to the sample composition, and for observed events.		pdf/eps
Evaluation of the Z+2 jet probability for simulated events, scaled by expected contribution to the sample composition, and for observed events.		pdf/eps
Evaluation of the WW+2 jet probability for simulated events, scaled by expected contribution to the sample composition, and for observed events.		pdf/eps
Evaluation of the W+3 jet probability for simulated events, scaled by expected contribution to the sample composition, and for observed events.		pdf/eps
Projected statistical error for this method.		pdf/eps