$B\to \rho l\bar{\nu }$ and $\omega l\bar{\nu }$ in and beyond the Standard Model: Improved predictions and $|V_{ub}|$

Abstract

We revisit the experimental and theoretical status of $B\to \rho l\bar{\nu }$ and $B\to \omega l\bar{\nu }$ decays. We perform a combined fit of averaged spectra from Belle and Babar measurements with prior light cone sum rule calculations, in order to obtain more precise predictions over the full $q^2$ range. The extracted values of $|V_{ub}|$ from these combined fits exhibit smaller uncertainty compared to previous extractions from $B\to \rho l\bar{\nu }$ and $B\to \omega l\bar{\nu }$ decays and the central values are found to be smaller than values extracted from $B\to \pi l\nu$ or inclusive measurements. We use our fit results to obtain more precise predictions in and beyond the Standard Model for the lepton universality ratios $R(\rho )$ and $R(\omega )$, as well as several angular observables that are sensitive to the full $q^2$ distribution, such as the longitudinal polarization of the vector meson, the $\tau$ polarization, and its forward-backward asymmetry.

Fixes and clarifies sign convention of tau polarization in Table V

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Cited by in corpus (12)

• Toward a complete description of $b\to u{\ell }^{-}\bar{\nu }$ decays within the Weak Effective Theory
• Extractions of $|V_{ub}|/|V_{cb}|$ from a combined study of the exclusive $b\to u(c)\ell {\nu }_{\ell }$ decays
• $B\to \rho \ell \bar{\nu }$ resonance form factors from $B\to \pi \pi \ell \bar{\nu }$ in lattice QCD
• On sum rules for semi-leptonic $b\to c$ and $b\to u$ decays
• A closer look at observables from exclusive semileptonic $B\to (\pi ,\rho )\ell {\nu }_{\ell }$ decays
• Measurement of Differential Branching Fractions of Inclusive $B\to X_u{\ell }^{+}{\nu }_{\ell }$ Decays
• A model-independent parameterization of $B\to \pi \pi \ell \nu$ decays
• First Simultaneous Determination of Inclusive and Exclusive $\left|V_{ub}\right|$
• Role of $\rho -\omega$ interference in semileptonic $B\to {\pi }^{+}{\pi }^{-}\ell {\bar{\nu }}_{\ell }$ decays
• Exploring the $\tau$ polarization in $B\to X\tau \bar{\nu }$ along different axes
• Recent progress in decays of $b$ and $c$ hadrons
• Measurement of inclusive $B\to X_u\ell \nu$ partial branching fractions and $|V_{ub}|$ at Belle II