$B\to D^{\ast }\ell \nu$ at non-zero recoil

Abstract

The current status of the lattice-QCD calculations of the form factors of the $B\to D^{\ast }\ell \nu$ semileptonic decay is reviewed. Particular emphasis is given to the most mature calculation at non-zero recoil coming from the Fermilab Lattice and MILC collaborations. Blinded, preliminary results for the form factors are shown, including a preliminary, but detailed error budget. The lattice results seem to favor a large slope at small recoil, in contrast to the latest untagged results coming from the Belle collaboration. A comprehensive comparison between the latest BGL $z$ expansions of Belle, Babar, the lattice and a joint BGL fit including lattice and Belle data is presented, and a roadmap to improve the current calculation is discussed. The current implications for $V_{cb}$ and $R(D^{\ast })$ are discussed.

arXiv comment8 pages, 12 figures. Proceedings of the 2019 Conference on Flavor Physics and CP Violation (FPCP2019). v2 fixes the contour plots of the coefficients of the BGL expansion for BaBar results (b1/b0 and c1/c0)

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Cited by in corpus (3)

• Theory determination of $\bar{B}\to D^{(\ast )}{\ell }^{-}\bar{\nu }$ form factors at $\mathcal{O}(1/m_c^2)$
• Precision Model-Independent Bounds from Global Analysis of $b\to c\ell \nu$ Form Factors
• Lepton Flavor Universality tests through angular observables of $\overline{B}\to D^{(\ast )}\ell \overline{\nu }$ decay modes