Searches for B⁰→ K⁺π^-τ⁺τ^- and B_s⁰→ K⁺K^-τ⁺τ^- decays

2025/10/15 by LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb +2372 · 2 voices
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #hep-ex

paper · pdf · doi:10.48550/arxiv.2510.13716

arxiv published 2025/10/15 · arxiv updated 2026/05/11

Abstract

The first searches for B⁰→ K⁺π^-τ⁺τ^- and B⁰_s→ K⁺K^-τ⁺τ^- decays at the LHCb experiment are conducted with pp collision data corresponding to an integrated luminosity of 5.4\textrm fb^-1. The tau leptons are reconstructed using the τ⁺→ μ⁺ν_τν_μ decay and the results are presented in bins of K⁺π^- or K⁺K^- mass. No signal is observed and upper limits are set on the branching fractions. The searches result in the first upper limits for B⁰→ K⁺π^-τ⁺τ^- decays outside the K^*(892)⁰ region in K⁺π^- mass and the first limits for B⁰_s→ K⁺K^-τ⁺τ^- decays. The searches are recast into limits on the decays B⁰→ K^*(892)⁰τ⁺τ^- and B⁰_s→ φ(1020)τ⁺τ^-, yielding 2.8×10^-4 (2.5×10^-4) and 4.7×10^-4 (4.1×10^-4) at the 95% (90%) confidence level, respectively. For the decay B⁰→ K^*(892)⁰τ⁺τ^-, this result improves on the current best upper limit by an order of magnitude.

Citations

• Search for B⁰ → K^{∗ 0} τ⁺ τ^- decays at the Belle II experiment
• A test of lepton flavor universality with a measurement of R(D^*) using hadronic B tagging at the Belle II experiment
• Flavor Phenomenology of the Leptoquark Singlet-Triplet Model
• Optuna: A Next-generation Hyperparameter Optimization Framework
• flavio: a Python package for flavour and precision phenomenology in the Standard Model and beyond
• Lepton universality violation and lepton flavor conservation in B-meson decays
• Evidence for an Excess of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mover accent="true"><mml:mi>B</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mo>→</mml:mo><mml:msup><mml:mi>D</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mo>*</mml:mo><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:msup><mml:msup><mml:mi>τ</mml:mi><mml:mo>−</mml:mo></mml:msup><mml:msub><mml:mover accent="true"><mml:mi>ν</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi>τ</mml:mi></mml:msub></mml:math>Decays
• Geant4 developments and applications
• Sensitivity of searches for new signals and its optimization
• Presentation of search results: the CL s technique

Discussions

• Searches for B⁰→K⁺π⁻τ⁺τ⁻ and Bₛ⁰→K⁺K⁻τ⁺τ⁻ decays arxiv.org/abs/2510.13716 - This is he first limit for the Bₛ⁰→K⁺K⁻τ⁺τ⁻ decay. For the decay B⁰→K*(892)⁰τ⁺τ⁻, this result improves on the current best u [bsky, 3 points, 0 comments]
• #LHCbpaper: Searches for B⁰ → K⁺π⁻τ⁺τ⁻ and B⁰_s → K⁺K⁻τ⁺τ⁻ decays (arXiv:2510.13716) https://arxiv.org/abs/2510.13716 [bsky, 0 points, 0 comments]

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