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An improved determination of the width of the top quark

Abstract : We present an improved determination of the total width of the top quark, $\Gamma_t$, using 5.4 fb$^{-1}$ of integrated luminosity collected by the D0 Collaboration at the Tevatron $p\bar{p}$ Collider. The total width $\Gamma_t$ is extracted from the partial decay width $\Gamma(t\to Wb)$ and the branching fraction $\mathcal{B}(t\to Wb)$. $\Gamma(t\to Wb)$ is obtained from the $t$-channel single top quark production cross section and $\mathcal{B}(t\to Wb)$ is measured in $t\bar{t}$ events. For a top mass of $172.5\;\rm GeV$, the resulting width is $\Gamma_t = 2.00^{+0.47}_{-0.43}$ GeV. This translates to a top-quark lifetime of $\tau_t = (3.29^{+0.90}_{-0.63})\times10^{-25}$ s. We also extract an improved direct limit on the CKM matrix element $0.81 < |V_{tb}| \leq 1$ at 95% C.L. and a limit of $|V_{tb'}| < 0.59$ for a high mass fourth generation bottom quark assuming unitarity of the fourth generation quark mixing matrix.
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Submitted on : Friday, January 20, 2012 - 1:41:58 PM
Last modification on : Thursday, December 16, 2021 - 2:11:16 PM

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V.M. Abazov, F. Badaud, U. Bassler, G. Bernardi, M. Besancon, et al.. An improved determination of the width of the top quark. Physical Review D, American Physical Society, 2012, 85, pp.091104(R). ⟨10.1103/PhysRevD.85.091104⟩. ⟨in2p3-00661675⟩



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