A Direct Top-Quark Width Measurement from Lepton + Jets Events at CDF II

• Published in: Physical review letters 2010-08, Vol.105
• Main Authors: Aaltonen, T., Alvarez Gonzalez, B., Amerio, S., Amidei, D., Anastassov, A., Annovi, A., Antos, J., Apollinari, G., Appel, J.A., Apresyan, A., Arisawa, T., Artikov, A., Asaadi, J., Ashmanskas, W., Auerbach, B., Aurisano, A., Azfar, F., Badgett, W., Barbaro-Galtieri, A., Barnes, V.E., Barnett, B.A., Barria, P., Bartos, P., Bauce, M., Bauer, G., Bedeschi, F., Beecher, D., Behari, S., Bellettini, G., Bellinger, J., Benjamin, D., Beretvas, A., Bhatti, A., Binkley, M., Bisello, D., Bizjak, I., Bland, K.R., Blocker, C., Blumenfeld, B., Bocci, A., Bodek, A., Bortoletto, D., Boudreau, J., Boveia, A., Brau, B., Brigliadori, L., Brisuda, A., Bromberg, C., Brucken, E., Bucciantonio, M., Budagov, J., Budd, H.S., Budd, S., Burkett, K., Busetto, G., Bussey, P., Buzatu, A., Cabrera, S., Calancha, C., Camarda, S., Campanelli, M., Campbell, M., Canelli, F., Canepa, A., Carls, B., Carlsmith, D., Carosi, R., Carrillo, S., Carron, S., Casal, B., Casarsa, M., Castro, A., Catastini, P., Cauz, D., Cavaliere, V., Cavalli-Sforza, M., Cerri, A., Cerrito, L., Chen, Y.C., Chertok, M., Chiarelli, G., Chlachidze, G., Chlebana, F., Cho, K., Chokheli, D., Chou, J.P., Chung, W.H., Chung, Y.S., Ciobanu, C.I., Ciocci, M.A., Clark, A., Clark, D., Compostella, G., Convery, M.E., Conway, J., Corbo, M., Cordelli, M., Cox, C.A., Cox, D.J., Crescioli, F.
• Format: Article
• Language: English
• Subjects: High Energy Physics - Experiment; Physics
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.105.232003

We present a measurement of the top-quark width using $t\bar{t}$ events produced in $p\bar{p}$ collisions at Fermilab's Tevatron collider and collected by the CDF II detector. In the mode where the top quark decays to a $W$ boson and a bottom quark, we select events in which one $W$ decays leptonically and the other hadronically~(lepton + jets channel) . From a data sample corresponding to 4.3~fb$^{-1}$ of integrated luminosity, we identify 756 candidate events. The top-quark mass and the mass of $W$ boson that decays hadronically are reconstructed for each event and compared with templates of different top-quark widths~($\Gamma_t$) and deviations from nominal jet energy scale~($\Delta_{JES}$) to perform a simultaneous fit for both parameters, where $\Delta_{JES}$ is used for the {\it 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 $\Gamma_t