Semitauonic B Decay Anomaly

The anomalously large experimentally measured ratios of the semitauonic decay $Brightarrow D^{(*)} +tau+ u$ and the corresponding semileptonic $Brightarrow D^{*} +l+bar{ u}_l$ disagree with the predictions of the standard E.W + QCD model(S.M). We briefly comment on this disagreement and on possible new physics explanations which are rather constrained and difficult to implement.