$B$ Flavour Anomalies: 2021 Theoretical Status Report

Abstract

At the present time, there are discrepancies with the predictions of the SM in several observables involving $b\to s{\ell }^{+}{\ell }^{-}$ and $b\to c{\ell }^{-}{\bar{\nu }}_{\ell }$ decays. These are the $B$ flavour anomalies. In this review, we summarize the data as of Moriond 2021 and present theoretical new-physics explanations from both a model-independent effective-field-theory point of view and through the building of explicit models. Throughout, we stress the complementarity of these two approaches. We also discuss combined explanations of both $B$ anomalies, and present models that also explain other problems, such as dark matter, $(g-2{)}_{\mu }$, neutrino properties, and hadronic anomalies.

48 pages, 1 figure. To be published in the Annual Review of Nuclear and Particle Science. Changes: minor modifications of the text, references updated and added

References in corpus (70)

• Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm
• Test of lepton universality using $B^{+}\to K^{+}{\ell }^{+}{\ell }^{-}$ decays
• B-physics anomalies: a guide to combined explanations
• Explaining $h\to {\mu }^{\pm }{\tau }^{\mp }$, $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ and $B\to K{\mu }^{+}{\mu }^{-}/B\to K{e}^{+}{e}^{-}$ in a two-Higgs-doublet model with gauged $L_{\mu }-L_{\tau }$
• Test of lepton universality in beauty-quark decays
• Addressing the LHC flavour anomalies with horizontal gauge symmetries
• $R_K$ and future $b\to s\ell \ell$ BSM opportunities
• Implications of lepton flavor universality violations in B decays
• NNLO QCD corrections to the B -> X_s gamma matrix elements using interpolation in m_c
• Simultaneous Explanation of the $R_K$ and $R(D^{(\ast )})$ Puzzles
• Gauge leptoquark as the origin of B-physics anomalies
• The lifetime of the $B_c^{-}$ meson and the anomalies in $B\to D^{(\ast )}\tau \nu$
• Baryon Number and Lepton Universality Violation in Leptoquark and Diquark Models
• New physics in the weak interaction of $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$
• $SU(2)\times U(1)$ gauge invariance and the shape of new physics in rare $B$ decays
• Measurement of the $\tau$ lepton polarization and $R(D^{\ast })$ in the decay $\bar{B}\to D^{\ast }{\tau }^{-}{\bar{\nu }}_{\tau }$ with one-prong hadronic $\tau$ decays at Belle
• Leptoquark model to explain the $B$-physics anomalies, $R_K$ and $R_D$
• Explaining Dark Matter and $B$ Decay Anomalies with an $L_{\mu }-L_{\tau }$ Model
• On the impact of power corrections in the prediction of B->K*mu+mu- observables
• Family non-universal Z' models with protected flavor-changing interactions
• Simultaneous Explanation of the $R_K$ and $R_{D^{(\ast )}}$ Puzzles: a Model Analysis
• On the single leptoquark solutions to the $B$-physics anomalies
• Lepton universality violation and lepton flavor conservation in $B$-meson decays
• Reading the footprints of the B-meson flavor anomalies
• Phenomenology of an $SU(2)\times SU(2)\times U(1)$ model with lepton-flavour non-universality
• New Physics effect on $B_c\to J/\psi \tau \bar{\nu }$ in relation to the $R_{D^{(\ast )}}$ anomaly
• Lepton Flavor Non-Universality in B decays from Dynamical Yukawas
• Scalar leptoquarks and the rare B meson decays
• Constraint on the branching ratio of B_c \to tau nu from LEP1 and consequences for R(D(*)) anomaly
• Non-local matrix elements in $B_{(s)}\to \{K^{(\ast )},\varphi \}{\ell }^{+}{\ell }^{-}$
• Logarithmically Enhanced Corrections to the Decay Rate and Forward Backward Asymmetry in anti-B --> X(s) l+ l-
• Implications of new evidence for lepton-universality violation in $b\to s{\ell }^{+}{\ell }^{-}$ decays
• A New Light Particle in B Decays?
• QED Corrections in $\bar{B}\to \bar{K}{\ell }^{+}{\ell }^{-}$ at the Double-Differential Level
• More Indications for Lepton Nonuniversality in $b\to s{\ell }^{+}{\ell }^{-}$
• Probing New Physics with $q^2$ distributions in $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$
• Unified Framework for $B$-Anomalies, Muon $g-2$, and Neutrino Masses
• A Model of Muon Anomalies
• 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
• $B$ decay anomalies and dark matter from vectorlike confinement
• Combined explanations of $(g-2{)}_{\mu }$, $R_{D^{(\ast )}}$, $R_{K^{(\ast )}}$ anomalies in a two-loop radiative neutrino mass model
• Flavourful $Z^{\prime }$ models for $R_{K^{(\ast )}}$
• A Minimal Explanation of Flavour Anomalies: B-Meson Decays, Muon Magnetic Moment, and the Cabibbo Angle
• Muonic Force Behind Flavor Anomalies
• Combined Explanation of the $Z\to b\bar{b}$ Forward-Backward Asymmetry, the Cabibbo Angle Anomaly, $\tau \to \mu \nu \nu$ and $b\to s{\ell }^{+}{\ell }^{-}$ Data
• Leptoquarks and Matter Unification: Flavor Anomalies and the Muon $g-2$
• A minimal flavored $U(1{)}^{\prime }$ for $B$-meson anomalies
• Unified SU(4) theory for the $R_{D^{(\ast )}}$ and $R_{K^{(\ast )}}$ anomalies
• Dirac dark matter and $b\to s{\ell }^{+}{\ell }^{-}$ with $\mathrm{U}(1)$ gauge symmetry
• Bayesian analysis of $b\to s{\mu }^{+}{\mu }^{-}$ Wilson coefficients using the full angular distribution of ${\Lambda }_b\to \Lambda (\to p{\pi }^{-}){\mu }^{+}{\mu }^{-}$ decays
• New Physics in Rare B Decays after Moriond 2021
• On Light Resonance Interpretations of the B Decay Anomalies
• Anomalous $Z^{\prime }$ bosons for anomalous $B$ decays
• New physics in $b\to s{e}^{+}{e}^{-}$?
• $U(1{)}_{B_3-L_2}$ Explanation of the Neutral Current $B-$Anomalies
• A Measurable Angular Distribution for $\bar{B}\to D^{\ast }{\tau }^{-}{\bar{\nu }}_{\tau }$ Decays
• A new $B$-flavour anomaly in $B_{d,s}\to K^{\ast 0}{\bar{K}}^{\ast 0}$: anatomy and interpretation
• $B$ decay anomalies from nonabelian local horizontal symmetry
• Dark matter and $B$-meson anomalies in a flavor dependent gauge symmetry
• Flavour anomalies and the muon $g-2$ from feebly interacting particles
• Collider Signatures of Coannihilating Dark Matter in Light of the B-Physics Anomalies
• A complete description of P- and S-wave contributions to the $B^0\to K^{+}{\pi }^{-}{\ell }^{+}{\ell }^{-}$ decay
• A vector leptoquark interpretation of the muon $g-2$ and $B$ anomalies
• Muon $(g-2)$ and Flavor Puzzles in the $U(1{)}_X^{}$-gauged Leptoquark Model
• $b\to s{\mu }^{+}{\mu }^{-}$ anomalies and related phenomenology in $U(1{)}_{B_3-x_{\mu }{L}_{\mu }-x_{\tau }{L}_{\tau }}$ flavor gauge models
• Flavor Specific $U(1{)}_{B_q-L_{\mu }}$ Gauge Model for Muon $g-2$ and $b\to s\bar{\mu }\mu$ Anomalies
• Charged Higgs bosons from the 3-3-1 models and the $\mathcal{R}(D^{(\ast )})$ anomalies
• Electroweak Penguin Decays of $b$-Flavoured Hadrons
• Beyond SMEFT with $b\to c{\tau }^{-}\bar{\nu }$
• Fermiophobic $Z^{\prime }$ model for simultaneously explaining the muon anomalies $R_{K^{(\ast )}}$ and $(g-2{)}_{\mu }$

Cited by in corpus (42)

• To (b)e or not to (b)e: No electrons at LHCb
• $b\to s\ell \ell$ Global Fits after $R_{K_S}$ and $R_{K^{\ast +}}$
• Confronting the vector leptoquark hypothesis with new low- and high-energy data
• Impact of ${\Lambda }_b\to {\Lambda }_c\tau \nu$ measurement on New Physics in $b\to cl\nu$ transitions
• Test of lepton flavor universality in B${}^{\pm }$ $\to$ K${}^{\pm }{\mu }^{+}{\mu }^{-}$ and B${}^{\pm }$ $\to$ K${}^{\pm }$e${}^{+}$e${}^{-}$ decays in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Electroweak-flavour and quark-lepton unification: a family non-universal path
• Global fit to $b\to c\tau \nu$ anomalies as of Spring 2024
• Review of Semileptonic $B$ Anomalies
• Enriching the physics program of the CMS experiment via data scouting and data parking
• A leptoquark and vector-like quark extended model for the simultaneous explanation of the $W$ boson mass and muon $g-2$ anomalies
• A new puzzle in non-leptonic B decays
• New physics in $B\to K^{\ast }{\tau }^{+}{\tau }^{-}$: A model independent analysis
• Constraints on $Z^{\prime }$ solutions to the flavor anomalies with trans-Planckian asymptotic safety
• A U-spin Puzzle in $B$ Decays
• Indirect constraints on lepton-flavour-violating quarkonium decays
• Constraints on leptoquarks from lepton-flavour-violating tau-lepton processes
• On sum rules for semi-leptonic $b\to c$ and $b\to u$ decays
• Interplay of the charged Higgs effects in $R_{D^{(\ast )}}$, $b\to s{\ell }^{+}{\ell }^{-}$ and $W$-mass
• A twisted tale of the transverse-mass tail
• Strange processes in general two Higgs doublet model
• Linking the $R_{K^{(\ast )}}$ anomalies to the Hubble tension via a single right-handed neutrino
• Prediction of various observables for $B_s^0\to D_s^{(\ast )-}{\ell }^{+}{\nu }_{\ell }$ within covariant confined quark model
• Exploring New Physics in transition $b\to s{\ell }^{+}{\ell }^{-}$ through different $B_c\to D_s^{(\ast )}{\ell }^{+}{\ell }^{-}$ observables
• $B_c^{-}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau },{\rho }^{-}{\nu }_{\tau },{\ell }^{-}{\bar{\nu }}_{\ell }{\nu }_{\tau }){\bar{\nu }}_{\tau }$ decays with visible final-state kinematics
• Anomalous gauge couplings vis-$\grave{a}$-vis $(g-2{)}_{\mu }$ and flavor observables
• Investigating New Physics through the Observables of Semileptonic $B_s\to K^{\ast }(\to K\pi ){\mu }^{+}{\mu }^{-}$ Decay
• Search for $B{}_s^0\to {\ell }^{\mp }{\tau }^{\pm }$ with the Semi-leptonic Tagging Method at Belle
• Dimension-5 baryon-number violation in low-scale Pati-Salam
• Lepton Flavor Violating $B\to K_2^{\ast }(1430){\mu }^{\pm }{\tau }^{\mp }$ Decays
• Searching and identifying leptoquarks through low-energy polarized scattering processes $e^{-}p\to e^{-}{\Lambda }_c$
• Electric Dipole Moments as Probes of $B$ Anomaly
• Charged Lepton Flavor Violation at the High-Energy Colliders: Neutrino Mass Relevant Particles
• Theoretical Review of Rare B Decays
• Decay $B_c^{+}\to D_{(s)}^{(\ast )+}{\ell }^{+}{\ell }^{-}$ within covariant confined quark model
• Round table on Standard Model Anomalies
• Addressing the $R_{\tau /\mu ,e}\left(D^{(\ast )}\right)$ puzzle through New Physics four-fermion operators and their impact on ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ decay
• First measurement of time-dependent $CP$ violation in the flavor-changing neutral-current decay $B^0\to K_S^0{\mu }^{+}{\mu }^{-}$
• The $B$ Anomalies, the $U_1$ Leptoquark and Dark Matter
• Observation of tWZ production at the CMS experiment
• Weak Annihilation Contribution to Angular Observables in $B_c^{+}\to D^{\ast +}{\ell }^{+}{\ell }^{-}$ Decays
• Real and Complex Singlet-Scalar Benchmarks with a Vector-Like Down Quark for $B\to X_s\gamma$ and $B_s-{\bar{B}}_s$ Mixing
• The Angular Observables of ${\Lambda }_b\to {\Lambda }_c(\to {\Lambda }^0{\pi }^{+}){\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau }){\bar{\nu }}_{\tau }$ within the Paradigm of FCCC Anomalies