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An improved determination of the width of the top quark

Research output: Contribution to journalJournal article


Article number091104(R)
<mark>Journal publication date</mark>4/05/2012
<mark>Journal</mark>Physical Review D
Issue number9
<mark>Original language</mark>English


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 $|V_{tb}| 0.59$ for a high mass fourth generation bottom quark assuming unitarity of the fourth generation quark mixing matrix.

Bibliographic note

© 2012 American Physical Society

8 pages, 4 figures, submitted to Phys. Rev. D (RC)