Speaker
Description
We develop a modified power-counting within the heavy quark effective theory (HQET),
that results in a highly constrained set of second-order power corrections in the heavy quark expansion, compared to the standard approach. We implement this modified expansion to determine all $\bar{B} \to D^{(*)}$ form factors, both within and beyond the Standard Model, to $\mathcal{O}(\alpha_s, \alpha_s/m_{c,b}, 1/m_{c,b}^2)$. Using measured $\bar{B} \to D^{(*)} \ell \bar\nu$ differential branching fractions for light leptons ($\ell = e$, $\mu$), we constrain not only leading and subleading Isgur-Wise functions, but also the $1/m_{c,b}^2$ corrections from subsubleading terms. We provide updated precision predictions for $\bar{B} \to D^{(*)} \tau \bar\nu$ decay rates, lepton universality ratios, and the CKM matrix element $|V_{cb}|$.
| In-person participation | Yes |
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