We present a measurement of the top-quark width in the lepton+jets decay channel of tt̄ events produced in pp̄ collisions at Fermilab's Tevatron collider and collected by the CDF II detector. From a data sample corresponding to 4.3fb⊃-1 of integrated luminosity, we identify 756 candidate events. The top-quark mass and the mass of the hadronically decaying W boson that comes from the top-quark decay are reconstructed for each event and compared with templates of different top-quark widths (Γt) and deviations from nominal jet energy scale (ΔJES) to perform a simultaneous fit for both parameters, where ΔJES is used for the in situ calibration of the jet energy scale. By applying a Feldman-Cousins approach, we establish an upper limit at 95% confidence level (CL) of Γt<7.6GeV and a two-sided 68% CL interval of 0.3GeV<Γt<4.4GeV for a top-quark mass of 172.5GeV/c2, which are consistent with the standard model prediction. © 2010 The American Physical Society.
Publication Source (Journal or Book title)
Physical Review Letters
Aaltonen, T., Álvarez González, B., Amerio, S., Amidei, D., Anastassov, A., Annovi, A., Antos, J., Apollinari, G., Appel, J., Apresyan, A., Arisawa, T., Artikov, A., Asaadi, J., Ashmanskas, W., Auerbach, B., Aurisano, A., Azfar, F., Badgett, W., Barbaro-Galtieri, A., Barnes, V., Barnett, B., Barria, P., Bartos, P., Bauce, M., Bauer, G., Bedeschi, F., Beecher, D., & Behari, S. (2010). Direct top-quark width measurement at CDF. Physical Review Letters, 105 (23) https://doi.org/10.1103/PhysRevLett.105.232003