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.
Measurement of the $\tau$ lepton polarization and $R(D^*)$ in the decay $\bar{B} \to D^* \tau^- \bar{\nu}_\tau$
7 Pith papers cite this work. Polarity classification is still indexing.
abstract
We report the first measurement of the $\tau$ lepton polarization $P_\tau(D^*)$ in the decay $\bar{B} \rightarrow D^* \tau^- \bar{\nu}_\tau$ as well as a new measurement of the ratio of the branching fractions $R(D^{*}) = \mathcal{B}(\bar {B} \rightarrow D^* \tau^- \bar{\nu}_\tau) / \mathcal{B}(\bar{B} \rightarrow D^* \ell^- \bar{\nu}_\ell)$, where $\ell^-$ denotes an electron or a muon, and the $\tau$ is reconstructed in the modes $\tau^- \rightarrow \pi^- \nu_\tau$ and $\tau^- \rightarrow \rho^- \nu_\tau$. We use the full data sample of $772 \times 10^6$ $B{\bar B}$ pairs recorded with the Belle detector at the KEKB electron-positron collider. Our results, $P_\tau(D^*) = -0.38 \pm 0.51 {\rm (stat.)} ^{+0.21}_{-0.16} {\rm (syst.)}$ and $R(D^*) = 0.270 \pm 0.035{\rm (stat.)} ^{+0.028}_{-0.025}{\rm (syst.)}$, are consistent with the theoretical predictions of the Standard Model.
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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.
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.
Measures Br(D_s^+ → μ^+ ν_μ) = (0.5294 ± 0.0108_stat ± 0.0085_syst)% and extracts f_{D_s^+} |V_cs| = 241.8 ± 4.7 MeV.
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.
LHCb measures R(D*) and R(J/ψ); combined LHCb+Belle data yield 3.1σ tension with SM in R(D) and R(D*).
citing papers explorer
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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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New physics searches via angular distributions of $ \bar{B} \to D^* (\to D \pi) \tau (\to \ell \nu_\tau \bar{\nu}_\ell) \bar{\nu}_\tau$ decays
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.
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Flavour anomalies and (fundamental) partial compositeness
Partial compositeness in the minimal fundamental partial compositeness (MFPC) model explains B-meson flavour anomalies while also solving the SM naturalness problem.
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Measurement of high-mass $t\bar{t}\ell^{+}\ell^{-}$ production and lepton flavour universality-inspired effective field theory interpretations at $\sqrt{s}=13$ TeV with the ATLAS detector
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.
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Improved measurement of the branching fraction of $D_s^+\to\mu^+\nu_\mu$
Measures Br(D_s^+ → μ^+ ν_μ) = (0.5294 ± 0.0108_stat ± 0.0085_syst)% and extracts f_{D_s^+} |V_cs| = 241.8 ± 4.7 MeV.
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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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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*).