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Abstract: We present a measurement of the top-quark width using $t\bar{t}$ eventsproduced in $p\bar{p}$ collisions at Fermilab-s Tevatron collider and collectedby the CDF II detector. In the mode where the top quark decays to a $W$ bosonand a bottom quark, we select events in which one $W$ decays leptonically andthe other hadronically~lepton + jets channel . From a data samplecorresponding to 4.3~fb$^{-1}$ of integrated luminosity, we identify 756candidate events. The top-quark mass and the mass of $W$ boson that decayshadronically are reconstructed for each event and compared with templates ofdifferent top-quark widths~$\Gamma t$ and deviations from nominal jet energyscale~$\Delta {JES}$ to perform a simultaneous fit for both parameters, where$\Delta {JES}$ is used for the {\it in situ} calibration of the jet energyscale. By applying a Feldman-Cousins approach, we establish an upper limit at95$\%$ confidence level~CL of $\Gamma t <$ 7.6 GeV and a two-sided 68$\%$ CLinterval of 0.3 GeV $< \Gamma t <$ 4.4 GeV for a top-quark mass of 172.5GeV$-c^2$, which are consistant with the standard model prediction. This is thefirst direct measurement of $\Gamma t$ to set a lower limit with 68$\%$ CL.



Autor: CDF Collaboration, T. Aaltonen, et al

Fuente: https://arxiv.org/







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