Plan for a B(t to Wb)/B(t to Wq) measurement in ttbar semi-leptonic decays at sqrt(s)=10 TeV

A feasibility study of the measurement of $R = B(t\rightarrow Wb)/B(t \rightarrow Wq)$, where $q=b,s,d$ in the semi-leptonic decay of $t \bar{t}$ events was performed. The measured observable is the probability to detect a given number of $b$-tagged jets, which depends on $R$ and on experimental issues ($b$-tagging efficiency and mis-tagging probability). We developed an analysis that makes minimal use of simulation and thus may be suitable for early measurements. With an integrated luminosity of 1 \ifb\ at $\sqrt{s}$=10 TeV the expected uncertainties on the $R$ parameter are $\sigma_{stat}=0.12$ and $\sigma_{syst}=0.11$