LHCb reports the first upper limits on B0 → K+π−τ+τ− and Bs0 → K+K−τ+τ− branching fractions, with recast limits of 2.8×10−4 on B0 → K*(892)0 τ+τ− at 95% CL that improve prior bounds by an order of magnitude.
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Huschle and others (Belle Collaboration),Measurement of the branching ratio of ¯B→D (∗)τ −¯ντ relative to ¯B→D (∗)ℓ−¯νℓ decays with hadronic tagging at Belle,Phys
13 Pith papers cite this work. Polarity classification is still indexing.
abstract
We report a measurement of the branching fraction ratios R(D(*)) of Bbar -> D(*) tau- nubar_tau relative to Bbar -> D()* l- nubar_l (where l = e or mu) using the full Belle data sample of 772 x 10^6 BBbar pairs collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. The measured values are R(D)= 0.375 +- 0.064(stat.) +- 0.026(syst.) and R(D*) = 0.293 +- 0.038(stat.) +- 0.015(syst.). The analysis uses hadronic reconstruction of the tag-side B meson and purely leptonic tau decays. The results are consistent with earlier measurements and do not show a significant deviation from the standard model prediction.
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representative citing papers
Including resonant contributions from LHCb muon data enhances standard model predictions for B to K(*) tau tau decays and makes short-distance new physics comparable to or larger than resonant effects over the full q2 range.
Introduces a reconstructible angular distribution for B to D* tau nu decays via tau to lepton chain to extract new physics parameters, projecting 5-6% sensitivities from simulation and lattice form factors.
Partial compositeness in the minimal fundamental partial compositeness (MFPC) model explains B-meson flavour anomalies while also solving the SM naturalness problem.
Angular observables in B→D(*)ℓν decays can distinguish Lorentz structures of new physics contributions fitted to measured R(D(*)) ratios, even when those ratios agree with the Standard Model.
ATLAS reports a measurement of high-mass ttbar ll production with no observed deviation from the Standard Model and derives EFT constraints on four-fermion operators from 140 fb^{-1} of Run 2 data.
Radiative corrections introduce up to 7% bias on R(D) measurements in LHCb-like pseudo-experiments when using PHOTOS for soft-photon simulation.
Four models for combined explanation of B anomalies are tested with general couplings, excluding three and constraining the fourth.
Semileptonic B decays to mixed axial-vector mesons show branching ratios and polarization observables that vary strongly with the D1 mixing angle in the covariant light-front quark model.
A tauphilic leptoquark model with S1 explaining R(D(*)), ~R2 fitting B to K nu nu via right-handed coefficients, and S3 satisfying Delta m_Bs via mixing predicts subdominant negative C_VL, dominant positive C_SL, C9^LQ approx +1, and masses below 3 TeV.
Model-independent calculation of differential branching ratio, forward-backward asymmetry, polarization, and angular coefficients in Bs → K* μ+μ- with 1D and 2D new physics scenarios in C7^NP, C9^(prime)NP, and C10^(prime)NP showing deviations from SM.
LHCb measures R(D*) and R(J/ψ); combined LHCb+Belle data yield 3.1σ tension with SM in R(D) and R(D*).
Review of the room left for B-decay anomalies inside the minimal low-energy leptoquark gauge model with SU(4)_C ⊗ SU(2)_L ⊗ U(1)_R symmetry.
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LHCb reports the first upper limits on B0 → K+π−τ+τ− and Bs0 → K+K−τ+τ− branching fractions, with recast limits of 2.8×10−4 on B0 → K*(892)0 τ+τ− at 95% CL that improve prior bounds by an order of magnitude.
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Impact of Hadronic Resonances on $B\to K^{(*)}\tau^+\tau^-$ decays
Including resonant contributions from LHCb muon data enhances standard model predictions for B to K(*) tau tau decays and makes short-distance new physics comparable to or larger than resonant effects over the full q2 range.
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Impacts of radiative corrections on measurements of lepton flavour universality in $B \to D \ell \nu_{\ell}$ decays
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Combined explanation of the B-anomalies
Four models for combined explanation of B anomalies are tested with general couplings, excluding three and constraining the fourth.
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A Phenomenological Study of Semileptonic $B^+$ and $B_s^0$ Decays into Axial-Vector Mesons $\big(D_1(2420),\, D_1^\prime(2430),\, D_{s1}(2460),\, \text{and } D_{s1}^\prime(2536)\big)$ within the Standard Model
Semileptonic B decays to mixed axial-vector mesons show branching ratios and polarization observables that vary strongly with the D1 mixing angle in the covariant light-front quark model.
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$B$ anomalies and the tauphilic leptoquark model
A tauphilic leptoquark model with S1 explaining R(D(*)), ~R2 fitting B to K nu nu via right-handed coefficients, and S3 satisfying Delta m_Bs via mixing predicts subdominant negative C_VL, dominant positive C_SL, C9^LQ approx +1, and masses below 3 TeV.
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Investigating New Physics through the Observables of Semileptonic $B_{s}\to K^{\ast}(\to K \pi)\mu^{+}\mu^{-}$ Decay
Model-independent calculation of differential branching ratio, forward-backward asymmetry, polarization, and angular coefficients in Bs → K* μ+μ- with 1D and 2D new physics scenarios in C7^NP, C9^(prime)NP, and C10^(prime)NP showing deviations from SM.
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Lepton flavour universality in charged-current $B$ decays
LHCb measures R(D*) and R(J/ψ); combined LHCb+Belle data yield 3.1σ tension with SM in R(D) and R(D*).
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Review of the room left for B-decay anomalies inside the minimal low-energy leptoquark gauge model with SU(4)_C ⊗ SU(2)_L ⊗ U(1)_R symmetry.