# An improved determination of the width of the top quark

6 D0
IPNL - Institut de Physique Nucléaire de Lyon
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.
Document type :
Journal articles

http://hal.in2p3.fr/in2p3-00661675
Contributor : Sylvie Flores <>
Submitted on : Friday, January 20, 2012 - 1:41:58 PM
Last modification on : Sunday, June 20, 2021 - 3:34:51 AM

### Citation

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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