Analyzing new physics in the decays ${\bar{B}}^0\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau }$ with form factors obtained from the covariant quark model

Abstract

We study possible New Physics (NP) effects in the exclusive decays ${\bar{B}}^0\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau }$. We extend the Standard Model (SM) by taking into account right-handed vector (axial), left- and right-handed (pseudo)scalar, and tensor current contributions. The ${\bar{B}}^0\to D^{(\ast )}$ transition form factors are calculated in the full kinematic $q^2$ range by employing a covariant quark model developed by us. We provide constraints on NP operators based on measurements of the ratios of branching fractions $R(D^{(\ast )})\equiv \mathcal{B}({\bar{B}}^0\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau })/\mathcal{B}({\bar{B}}^0\to D^{(\ast )}{\mu }^{-}{\bar{\nu }}_{\mu })$ and consider the effects of these operators on physical observables in different NP scenarios. We also derive the four-fold angular distribution for the cascade decay ${\bar{B}}^0\to D^{\ast +}(\to D^0{\pi }^{+}){\tau }^{-}{\bar{\nu }}_{\tau }$ which allows one to analyze the polarization of the $D^{\ast }$ meson in the presence of NP effects. We discuss several strategies to distinguish between various NP contributions.

31 pages, 10 figures, some corrections made, discussions extended, figures updated, references added; a version to appear in PRD

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Cited by in corpus (14)

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• Explaining the $R_K$ and $R_{D^{(\ast )}}$ anomalies with vector leptoquarks
• New Physics in the Visible Final States of $B\to D^{(\ast )}\tau \nu$
• Probing new physics in ${\bar{B}}^0\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau }$ using the longitudinal, transverse, and normal polarization components of the tau lepton
• On lepton flavour universality in semileptonic $B_c\to {\eta }_c,J/\psi$ decays
• Probing new physics in semileptonic ${\Lambda }_b$ decays
• Precision Model-Independent Bounds from Global Analysis of $b\to c\ell \nu$ Form Factors
• Decay $D\to K^{(\ast )}{\ell }^{+}{\nu }_{\ell }$ in covariant quark model
• Phenomenology of flavorful composite vector bosons in light of $B$ anomalies
• Probing new physics in semileptonic ${\Sigma }_b$ and ${\Omega }_b$ decays
• $D^{\ast }$ Polarization as an Additional Constraint on New Physics in the $b\to c\tau {\bar{\nu }}_{\tau }$ Transition
• A new angle on an old problem: Helicity approach to neutron beta decay in the Standard Model
• Anomalies in Weak Decays of Hadrons Containing a b Quark