Figure 1

(left) Standard model differential branching fractions and experiment. (right) Form factor, input parameter, and Wilson coefficient ($C_i$) contributions to the error. The total error is the sum in quadrature of the components. (a) Belle [11], BABAR [12], CDF [13], and LHCb [14,15] data and the Standard Model contribution to $d{\mathcal{B}}_{\ell }/d{q}^2$, $\ell =e$, $\mu$, (b) Error components for $d{\mathcal{B}}_{\ell }/d{q}^2$, (c) Predicted Standard Model contribution to $d{\mathcal{B}}_{\tau }/d{q}^2$, (d) Error components for $d{\mathcal{B}}_{\tau }/d{q}^2$.