We present an improved determination of the total width of the top quark, Γt, using 5.4 fb-1 of integrated luminosity collected by the D0 Collaboration at the Tevatron pp- Collider. The total width Γt is extracted from the partial decay width Γ(t →Wb) and the branching fraction Β(t → Wb). Γ(t → Wb) is obtained from the t-channel single top-quark production cross section and Β(t → Wb) is measured in tt- events. For a top mass of 172.5 GeV, the resulting width is Γt = 2.00 +0:47 - 0:43 GeV. This translates to a top-quark lifetime of τt = (3.29 +0:90 -0.63) x 10-25s. We also extract an improved direct limit on the Cabibbo- Kobayashi-Maskawa quark-mixing matrix element 0.81 < │Vtb│ ≤ 1 at 95% C.L. and a limit of │Vtb ‘│< 0.59 for a high-mass fourth-generation bottom quark assuming unitarity of the fourth-generation quark-mixing matrix.
Hedin, David, "Improved Determination of the Width of the Top Quark" (2012). Faculty Peer-Reviewed Publications. 1002.
Department of Physics
We thank the staffs at Fermilab and collaborating institutions, and acknowledge support from the DOE and NSF (USA); CEA and CNRS/IN2P3 (France); FASI, Rosatom, and RFBR (Russia); CNPq, FAPERJ, FAPESP, and FUNDUNESP (Brazil); DAE and DST (India); Colciencias (Colombia); CONACyT (Mexico); NRF (Korea); CONICET and UBACyT (Argentina); FOM (The Netherlands); STFC and the Royal Society (United Kingdom); MSMT and GACR (Czech Republic); BMBF and DFG (Germany); SFI (Ireland); The Swedish Research Council (Sweden); and CAS and CNSF (China).
American Physical Society