Improvement of heavy-heavy current for calculation of $\bar{B} o D^{(*)}\ell\bar{ u}$ form factors using Oktay-Kronfeld heavy quarks

摘要

The CKM matrix element $|V_{cb}|$ can be extracted by combining data fromexperiments with lattice QCD results for the semileptonic form factors for the$\bar{B}\to D^{(*)} \ell \bar{\nu}$ decays. The Oktay-Kronfeld (OK) action wasdesigned to reduce heavy-quark discretization errors to below $1\%$, or through$\mathcal{O}(\lambda^3)$ in HQET power counting. Here we describe recentprogress on bottom-to-charm currents improved to the same order in HQET as theOK action, and correct formerly reported results of our matching calculations,in which the operator basis was incomplete.