Precise determination of the W tb couplings at the CERN Large Hadron Collider

Top pair production at the CERN LHC is the ideal place to search for nonstandard Wtb couplings in t-->Wb-->lnub decays. The lb forward-backward asymmetry in the W rest frame is very sensitive to sigma(munu) couplings, and can spot one-loop QCD corrections to the decay vertex with more than 5sigma statistical significance. We discuss the potential of this asymmetry to signal nonstandard gamma(mu) and sigma(munu) couplings and compare with t (t) over bar spin correlation asymmetries, which have a lower sensitivity. We also briefly summarize the results for the Fermilab Tevatron.