Quest for New Physics with Ratio of CKM Elements

The CKM elements |V<inf>ub</inf>| and |V<inf>cb</inf>| show a discrepancy between the exclusive and inclusive determinations. These determinations are masked with hadronic and other uncertainties, and thus can’t be unambiguously taken as implying new physics. In this talk, we consider a new observable: the ratio of these two CKM elements, R<inf>V</inf>≡|V<inf>ub</inf>|/|V<inf>cb</inf>|, which is found to receive negligible corrections due to hadronic as well as QED effects. It is observed that the R<inf>V</inf> as constructed from exclusive determinations of |V<inf>ub</inf>| and |V<inf>cb</inf>| agrees quite well with that constructed from the inclusive determinations of these CKM elements. Hence, we show that R<inf>V</inf> is a cleaner observable, and can serve as an excellent tool for the test of the Standard Model.