Can the Differences in the Determinations of Vub and Vcb Be Explained by New Physics?

The precise determination of the Cabibbo-Kobayashi-Maskawa elements Vcb and Vub is crucial for any new physics analysis in the flavor sector. Their values can be determined from several tree-level decays: Vcb can be extracted from B → Dlv and B → D*lv while Vuh can be obtained from B → πlv, B → plv, and B→τv. In addition, for both Vcb and Vub an inclusive determination is available. There is a long lasting discrepancy between the inclusive and exclusive determinations which recently even increased for Vcb above the 3τ level. In this Letter we study the possible effect of new physics on the inclusive and exclusive determination of Vcb and Vuh in a model independent way. We find that there is only one operator corresponding to a modified W coupling which can achieve this. However, respecting SU(2) gauge invariance at the high scale this would lead to very large violations of the Z to bb coupling not compatible with experiment. Therefore, we conclude that a new physics explanation of the difference between the inclusive and exclusive determination of Vcb and Vub is currently ruled out. Therefore, the discrepancies must be due to underestimated uncertainties in the theoretical and/or the experimental analysis. [ABSTRACT FROM AUTHOR]