Remarks on the Standard Model predictions for $R(D)$ and $R(D^{\ast })$

Abstract

Semileptonic $b\to c$ transitions, and in particular the ratios $R(D^{(\ast )})=\frac{\Gamma (B\to D^{(\ast )}\tau \nu )}{\Gamma (B\to D^{(\ast )}\ell \nu )}$, can be used to test the universality of the weak interactions. In light of the recent discrepancies between the experimental measurements of these observables by BaBar, Belle and LHCb and the Standard Model predicted values, we study the robustness of the latter. Our analysis reveals that $R(D)$ might be enhanced by lepton mass effects associated to the mostly unknown scalar form factor. In constrast, the Standard Model prediction for $R(D^{\ast })$ is found to be more robust, since possible pollutions from $B^{\ast }$ contributions turn out to be negligibly small, which indicates that $R(D^{\ast })$ is a promising observable for searches of new physics.

arXiv comment11 pages, 3 figures; v2: minor corrections, matches published version

References in corpus (48)

• Evidence for an excess of B -> D(*) Tau Nu decays
• Measurement of the branching ratio of $\bar{B}\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau }$ relative to $\bar{B}\to D^{(\ast )}{\ell }^{-}{\bar{\nu }}_{\ell }$ decays with hadronic tagging at Belle
• Measurement of the ratio of branching fractions $\mathcal{B}({\overline{B}}^0\to D^{\ast +}{\tau }^{-}{\overline{\nu }}_{\tau })/\mathcal{B}({\overline{B}}^0\to D^{\ast +}{\mu }^{-}{\overline{\nu }}_{\mu })$
• One Leptoquark to Rule Them All: A Minimal Explanation for $R_{D^{(\ast )}}$, $R_K$ and $(g-2{)}_{\mu }$
• On the B to D* tau nu Sensitivity to New Physics
• Measurement of the branching ratio of ${\bar{B}}^0\to D^{\ast +}{\tau }^{-}{\bar{\nu }}_{\tau }$ relative to ${\bar{B}}^0\to D^{\ast +}{\ell }^{-}{\bar{\nu }}_{\ell }$ decays with a semileptonic tagging method
• Effective field theory approach to $b\to s\ell {\ell }^{(\prime )}$, $B\to K^{(\ast )}\nu \bar{\nu }$ and $B\to D^{(\ast )}\tau \nu$ with third generation couplings
• Anomalies in $B$-decays and $U(2)$ flavour symmetry
• Vector leptoquark resolution of $R_K$ and $R_{D^{(\ast )}}$ puzzles
• Testing leptoquark models in $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$
• Implications of lepton flavor universality violations in B decays
• Flavor models for $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$
• Explaining B->Dτν, B->D*τνand B->τνin a 2HDM of type III
• $B\to Dl\nu$ Form Factors at Non-Zero Recoil and Extraction of $|V_{cb}|$
• A perturbed lepton-specific two-Higgs-doublet model facing experimental hints for physics beyond the Standard Model
• Revisiting $B\to D\ell \nu$
• New physics in the weak interaction of $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$
• Non-abelian gauge extensions for B-decay anomalies
• Leptoquark model to explain the $B$-physics anomalies, $R_K$ and $R_D$
• Sensitivity to charged scalars in $B\to D^{(\ast )}\tau {\nu }_{\tau }$ and $B\to \tau {\nu }_{\tau }$ decays
• Leptoquark Flavor Patterns & B Decay Anomalies
• Phenomenology of an $SU(2)\times SU(2)\times U(1)$ model with lepton-flavour non-universality
• Minimally flavored colored scalar in $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$ and the mass matrices constraints
• On the anomalous enhancement observed in $B\to D^{(\ast )}\tau {\bar{\nu }}_{\tau }$ decays
• Towards a unified explanation of $R_{D^{(\ast )}}$, $R_K$ and $(g-2{)}_{\mu }$ anomalies in a left-right model with leptoquarks
• B decays with $\tau$-leptons in non-universal left-right models
• Sterile neutrinos in leptonic and semileptonic decays
• Hints of R-parity violation in B decays into $\tau \nu$
• New Physics in the Visible Final States of $B\to D^{(\ast )}\tau \nu$
• D* polarization as a probe to discriminate new physics in B --> D* tau nubar
• Measurement of the form factors of the decay B0 -> D*- ell+ nu and determination of the CKM matrix element |Vcb|
• B -> D^(*) tau nu and B -> tau nu in chiral U(1)' models with flavored multi Higgs doublets
• Optimal-observable analysis of possible new physics in $B\to D^{(\ast )}\tau {\nu }_{\tau }$
• New physics in the kinematic distributions of $\bar{B}\to D^{(\ast )}{\tau }^{-}(\to {\ell }^{-}{\bar{\nu }}_{\ell }{\nu }_{\tau }){\bar{\nu }}_{\tau }$
• Toward a coherent solution of diphoton and flavor anomalies
• Strong D* -> D+pi and B* -> B+pi couplings
• Measurement of the branching ratio of ${\bar{B}}^0\to D^{\ast +}{\tau }^{-}{\bar{\nu }}_{\tau }$ relative to ${\bar{B}}^0\to D^{\ast +}{\ell }^{-}{\bar{\nu }}_{\ell }$ decays with a semileptonic tagging method
• Leptoquark patterns unifying neutrino masses, flavor anomalies, and the diphoton excess
• Precision lattice QCD computation of the $B^{\ast }B\pi$ coupling
• Probing the R-parity violating supersymmetric effects in the exclusive b\to c\ell^-\barν_\ell decays
• $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$ excesses in ALRSM constrained from $B$, $D$ decays and $D^0-{\bar{D}}^0$ mixing
• Explaining the diphoton excess in Alternative Left-Right Symmetric Model
• Rare decays of B mesons via on-shell sterile neutrinos
• Radiative two-pion decay of the tau lepton
• The $B\to D^{(\ast )}l{\nu }_l$ decays in the pQCD approach with the Lattice QCD input
• The B*Bpi coupling using relativistic heavy quarks
• Impact of leptonic $\tau$ decays on the distribution of $B\to P\mu \bar{\nu }$ decays
• Study of semileptonic ${\bar{B}}^{\ast }\to P\ell {\bar{\nu }}_{\ell }$ decays

Cited by in corpus (11)

• Scalar contributions to $b\to c(u)\tau \nu$ transitions
• New physics solutions for $R_D$ and $R_{D^{\ast }}$
• Lepton universality violation and right-handed currents in $b\to c\tau \nu$
• D* polarization as a probe to discriminate new physics in B --> D* tau nubar
• 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
• Anomalies in (semi)-leptonic $B$ decays $B^{\pm }\to {\tau }^{\pm }\nu$, $B^{\pm }\to D{\tau }^{\pm }\nu$ and $B^{\pm }\to D^{\ast }{\tau }^{\pm }\nu$, and possible resolution with sterile neutrino
• Probing a simplified, $W^{\prime }$ model of $R(D^{(\ast )})$ anomalies using $b$-tags, $\tau$ leptons and missing energy
• Beyond $\mathcal{R}(D^{(\ast )})$ with the general 2HDM-III for $b\to c\tau \nu$
• $B_s\to D_s^{\ast }$ Form Factors for the full $q^2$ range from Lattice QCD
• Evaluation of CKM matrix elements from exclusive $P_{\ell 4}$ decays
• Closing the Gap on $R_{D^{\ast }}$ by including longitudinal effects