Impact of polarization observables and Bc → τν on new physics explanations of the b → cτν anomaly (vol 99, 075006, 2019)

In this addendum to Ref. [1], we update our results to include the recent measurement of R(D) and R(D*) by the Belle Collaboration [2]: R(D)(Belle) = 0.307 +/- 0.037 +/- 0.016 and R(D*)(Belle) = 0.283 +/- 0.018 +/- 0.014, resulting in the new HFLAV fit result R(D) = 0.340 +/- 0.027 +/- 0.013, R(D*) = 0.295 +/- 0.011 +/- 0.008, exhibiting a 3.1 sigma tension with the Standard Model. We present the new fit results and update all figures, including the relevant new collider constraints. The updated prediction for R(Lambda(c)) from our sum rule reads R(Lambda(c)) = R-SM (Lambda(c)) (1.15 +/- 0.04) = 0.38 +/- 0.01 +/- 0.01. We also comment on theoretical predictions for the fragmentation function f(c) of b -> B-c and their implication on the constraint from B-u/c -> tau nu data.