Measurement of the branching fractions and longitudinal polarisations of $B_{(s)}^0\to K^{\ast 0}\overline{K}{}^{\ast 0}$ decays

Abstract

A time- and flavour-integrated amplitude analysis of $B^0$ and $B_s^0$ decays to the $(K^{+}{\pi }^{-})(K^{-}{\pi }^{+})$ final state in the $K^{\ast }(892{)}^0\overline{K}{}^{\ast }(892{)}^0$ region is presented, using $pp$ collision data recorded with the LHCb detector in 2011--2018, corresponding to an integrated luminosity of $9{\text{fb}}^{-1}$. The branching fractions of the $B^0$ and $B_s^0$ decays are measured relative to the $B^0\to D^{-}{\pi }^{+}$ and $B_s^0\to D_s^{-}{\pi }^{+}$ modes, respectively. The corresponding longitudinal polarisation fractions are found to be $f_L^d=0.600\pm 0.022\pm 0.017$ and $f_L^s=0.159\pm 0.010\pm 0.007$, where the uncertainties are statistical and systematic, respectively. The theory-motivated ratio of the squared $B_s^0$ to $B^0$ longitudinally polarised decay amplitudes is found to be $L_{K^{\ast 0}\overline{K}{}^{\ast 0}}=4.92\pm 0.55\pm 0.48\pm 0.02\pm 0.10$, where the uncertainties are statistical, systematic, due to uncertainty of external mass and lifetime measurements, and due to knowledge of the fragmentation fraction ratio, respectively. This confirms the previously reported tension between experimental determinations and theoretical predictions of longitudinal polarisation in $B\to VV$ decays at the level of 4.4 standard deviations.

All figures and tables, along with any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/4535 (LHCb public pages)

References in corpus (27)

• PYTHIA 6.4 Physics and Manual
• Branching Ratio Measurements of $B_s$ Decays
• RapidSim: an application for the fast simulation of heavy-quark hadron decays
• Reweighting with Boosted Decision Trees
• Precise measurement of the $f_s/f_d$ ratio of fragmentation fractions and of $B_s^0$ decay branching fractions
• Dalitz plot analysis of Ds+ --> K+ K- pi+
• Improved Estimates of The $B_{(s)}\to VV$ Decays in Perturbative QCD Approach
• B_s to K^(*)0 \bar K^(*)0 decays: the golden channels for new physics searches
• Dispersive $\pi K\to \pi K$ and $\pi \pi \to K\bar{K}$ amplitudes from scattering data, threshold parameters and the lightest strange resonance $\kappa$ or $K_0^{\ast }(700)$
• Global Analysis of Charmless $B$ Decays into Two Vector Mesons in Soft-Collinear Effective Theory
• Measurements of the branching fractions of the decays $B_s^0\to D_s^{\mp }{K}^{\pm }$ and $B_s^0\to D_s^{-}{\pi }^{+}$
• A new $B$-flavour anomaly in $B_{d,s}\to K^{\ast 0}{\bar{K}}^{\ast 0}$: anatomy and interpretation
• Averages of $b$-hadron, $c$-hadron, and $\tau$-lepton properties as of 2023
• A new puzzle in non-leptonic B decays
• The LHCb Stripping Project: Sustainable Legacy Data Processing for High-Energy Physics
• Amplitude analysis of $B_s^0\to K_{\text{S}}^0{K}^{\pm }{\pi }^{\mp }$ decays
• Exclusive $B\to VV$ Decays and CP Violation in the General two-Higgs-doublet Model
• Studying New Physics Amplitudes in Charmless B_s Decays
• Amplitude analysis of the $B_{(s)}\to K^{\ast 0}{\overline{K}}^{\ast 0}$ decays and measurement of the branching fraction of the $B\to K^{\ast 0}{\overline{K}}^{\ast 0}$ decay
• Evidence for Neutral B Meson Decays to wK*0
• Updated branching fraction measurements of $B_{(s)}^0\to K_{\mathrm{S}}^0{h}^{+}{h}^{\prime -}$ decays
• Charmless $B\to PP,PV,VV$ Decays Based on the six-quark Effective Hamiltonian with Strong Phase Effects
• Generalized analysis on $B\to K^{\ast }\rho$ within and beyond the Standard Model $-$ Can it help understand the $B\to K\pi$ puzzle?
• Search for the decay $B^{+}\to \overline{K}{}^{\ast 0}{K}^{\ast +}$ at Belle
• A phenomenological estimate of rescattering effects in $B_s\to K^{\ast 0}{\bar{K}}^{\ast 0}$
• Impact on $L$-observables of a new combined analysis of $B_{d,s}\to K^{(\ast )}$ form factors
• First observation of $CP$ violation and measurement of polarization in $B^{+}\to \rho (770{)}^0{K}^{\ast }(892{)}^{+}$ decays

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