Probing R-parity violation in B-meson decays to a baryon and a light neutralino

We propose a search for B meson decays to a baryon plus missing energy at the Belle II experiment to probe supersymmetry with a GeV-scale lightest neutralino χ̃₁⁰ and R-parity violation (RPV). We perform analytic computations of the signal branching fractions in the framework of effective field theory, with a single nonzero RPV operator λ'ᵢⱼₖ Ũᵢ D̃ⱼᶜ D̃ₖᶜ, where i, j = 1, 2. The hadronic form factors are calculated using an SU(3) phenomenological Lagrangian approach for the proton, as well as several hyperons and charmed baryons. Since the decay of the neutralino is kinematically and CKM suppressed in this theoretical scenario, it decays outside the detector and appears experimentally only as missing energy. We detail the analysis techniques at the experimental level and estimate the background in the B⁺ → pχ̃₁⁰ search using published results for B⁺ → K⁺νν̄. Our final sensitivity plots are shown for both λ'₁₁₃ versus the squark mass mq̃ and λ'₁₁₃/m²q̃ versus the neutralino mass mχ̃₁⁰. We find that the search at Belle II could probe λ'₁₁₃/m²q̃ down to the order of 10⁻⁸ GeV⁻² in the kinematically allowed mχ̃₁⁰ range. We also obtain current limits on λ'₁₂₃ by recasting an existing search interpreted as B⁰ → Λ⁰χ̃₁⁰, and comment about searches for B⁺ → Σ⁺χ̃₁⁰, B⁰ → Σ⁰χ̃₁⁰, B⁺ → Λ⁺ᶜχ̃₁⁰, and B⁺ → Ξ⁺ᶜχ̃₁⁰. In closing, we briefly discuss potential searches at the LHCb and BESIII experiments.