Revisiting fits to $B^0\to D^{\ast -}{\ell }^{+}{\nu }_{\ell }$ to measure $|V_{cb}|$ with novel methods and preliminary LQCD data at non-zero recoil

Abstract

We present a study of fits to exclusive $B^0\to D^{\ast -}{\ell }^{+}{\nu }_{\ell }$ measurements for the determination of the Cabbibo-Kobayashi-Maskawa matrix element magnitude $|V_{cb}|$, based on the most recent Belle untagged measurement. Results are obtained with the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) form factor parametrizations, with and without the inclusion of preliminary Lattice QCD measurements of form factors at non-zero hadronic recoil from the JLQCD collaboration. The CLN and BGL fits are also studied in different scenarios with reduced theoretical assumptions, and at higher order expansions, respectively. To avoid bias from high systematic error correlations we employ a novel technique in the field of $B$-physics phenomenology with a toy MC using a Cholesky decomposition of the covariance matrix. Using additional input from Lattice QCD calculations of form factors at non-zero recoil, in collaboration with JLQCD, allows for well-defined fit results with reduced model dependence in CLN and BGL. The results obtained are consistent between different configurations, ultimately providing a method for a more model-independent exclusive measurement of $|V_{cb}|$. Using preliminary inputs, $\mathcal{F}(1){\eta }_{\mathrm{EW}}|V_{cb}|$ is found to be approximately $(35.02\pm 0.29\pm 0.88)\times 10^{-3}$ in BGL(2,2,2) and $(34.96\pm 0.32\pm 0.96)\times 10^{-3}$ in CLNnoHQS.

17 pages, 10 figures, 7 tables. Submitted to Physical Review D

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• Extraction of $|V_{cb}|$ from $B\to D^{(\ast )}\ell {\nu }_{\ell }$ and the Standard Model predictions of $R(D^{(\ast )})$
• The $V_{cb}$ puzzle: an update
• Tensions and correlations in $|V_{cb}|$ determinations
• Precise determination of the CKM matrix element $\left|V_{cb}\right|$ with ${\bar{B}}^0\to D^{\ast +}{\ell }^{-}{\bar{\nu }}_{\ell }$ decays with hadronic tagging at Belle

Cited by in corpus (12)

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• Lepton-flavour non-universality of $\bar{B}\to D^{\ast }\ell \bar{\nu }$ angular distributions in and beyond the Standard Model
• $|V_{cb}|$ and $R(D^{(\ast )})$ using lattice QCD and unitarity
• Publishing statistical models: Getting the most out of particle physics experiments
• Measurement of Differential Distributions of $B\to D^{\ast }\ell {\bar{\nu }}_{\ell }$ and Implications on $|V_{cb}|$
• $B\to D^{\ast }\ell {\nu }_{\ell }$ semileptonic form factors from lattice QCD with Möbius domain-wall quarks
• Determination of $|V_{cb}|$ using ${\overline{B}}^0\to D^{\ast +}{\ell }^{-}{\bar{\nu }}_{\ell }$ decays with Belle II
• A test of light-lepton universality in the rates of inclusive semileptonic $B$-meson decays at Belle II
• Loopy Determinations of $V_{ub}$ and $V_{cb}$
• First Measurement of $R(X_{\tau /\ell })$ as an Inclusive Test of the $b\to c\tau \nu$ Anomaly
• New determination of $|V_{\mathrm{cb}}|$ using the three-loop QCD corrections for the $B\to D^{\ast }$ semi-leptonic decays
• Measurement of the Ratio of Partial Branching Fractions of Inclusive $\overline{B}\to X_u\ell \overline{\nu }$ to $\overline{B}\to X_c\ell \overline{\nu }$ and the Ratio of their Spectra with Hadronic Tagging