Measurement of Differential Distributions of $B\to D^{\ast }\ell {\bar{\nu }}_{\ell }$ and Implications on $|V_{cb}|$

Abstract

We present a measurement of the differential shapes of exclusive $B\to D^{\ast }\ell {\bar{\nu }}_{\ell }$ ($B=B^{-},{\bar{B}}^0$ and $\ell =e,\mu$) decays with hadronic tag-side reconstruction for the full Belle data set of $711{\mathrm{fb}}^{-1}$ integrated luminosity. We extract the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) form factor parameters and use an external input for the absolute branching fractions to determine the Cabibbo-Kobayashi-Maskawa matrix element and find $|V_{cb}{|}_{\mathrm{CLN}}=(40.1\pm 0.9)\times 10^{-3}$ and $|V_{cb}{|}_{\mathrm{BGL}}=(40.6\pm 0.9)\times 10^{-3}$ with the zero-recoil lattice QCD point $\mathcal{F}(1)=0.906\pm 0.013$. We also perform a study of the impact of preliminary beyond zero-recoil lattice QCD calculations on the $|V_{cb}|$ determinations. Additionally, we present the lepton flavor universality ratio $R_{e\mu }=\mathcal{B}(B\to D^{\ast }e{\bar{\nu }}_e)/\mathcal{B}(B\to D^{\ast }\mu {\bar{\nu }}_{\mu })=0.990\pm 0.021\pm 0.023$, the electron and muon forward-backward asymmetry and their difference $\Delta A_{FB}=0.022\pm 0.026\pm 0.007$, and the electron and muon $D^{\ast }$ longitudinal polarization fraction and their difference $\Delta F_L^{D^{\ast }}=0.034\pm 0.024\pm 0.007$. The uncertainties quoted correspond to the statistical and systematic uncertainties, respectively.

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Cited by in corpus (12)

• FLAG Review 2024
• Global fit to $b\to c\tau \nu$ anomalies as of Spring 2024
• $B\to D^{\ast }\ell {\nu }_{\ell }$ semileptonic form factors from lattice QCD with Möbius domain-wall quarks
• Review of Semileptonic $B$ Anomalies
• Discriminating $B\to D^{\ast }\ell \nu$ form factors via polarization observables and asymmetries
• Determination of $|V_{cb}|$ using ${\overline{B}}^0\to D^{\ast +}{\ell }^{-}{\bar{\nu }}_{\ell }$ decays with Belle II
• Tests of light-lepton universality in angular asymmetries of $B^0\to D^{\ast -}\ell \nu$ decays
• The QED nonfactorizable correction to the semileptonic charmed three-body $B$ decays
• Lepton universality tests and searches for new physics in charged current decays at Belle II
• On magnitudes of some CKM matrix elements
• Observation of $D^{+}\to K_S^0{\pi }^0{\mu }^{+}{\nu }_{\mu }$, Test of Lepton Flavor Universality and First Angular Analysis of $D^{+}\to {\bar{K}}^{\ast }(892{)}^0{\ell }^{+}{\nu }_{\ell }$
• Determination of $|V_{cb}|$ using $B\to D\ell {\nu }_{\ell }$ Decays at Belle II