Solutions to RD-RD⁎ in light of Belle 2019 data

Abstract

Earlier this year, the Belle collaboration presented their new measurements of RD and RD⁎ using a new method. These measurements are consistent with the Standard Model predictions, whereas the global averages of the earlier measurements had a 4.1σ discrepancy. With the inclusion of the new data in the global averages, the discrepancy comes down to 3.1σ. In this work, we study the new physics solutions to the RD-RD⁎ anomaly allowed by the reduction in the discrepancy. Among the four fermion operators, which arise through a single particle exchange, only the (V−A) operator solution survives. We found three additional solutions with two dis-similar operators. The branching ratio of Bc→τν¯ is powerful discriminant between these four allowed solutions.