Search for baryogenesis and dark matter in B + → Λ

A mechanism of baryogenesis and dark matter production via B meson oscillations and decays has recently been proposed to explain the observed dark matter abundance and matter-antimatter asymmetry in the universe. This mechanism introduces a low-mass dark sector particle ( ψ D ) with a nonzero baryonic charge. We present a search for this new state in B + → Λ c + ψ D decays using data collected at the ϒ ( 4 S ) resonance by the detector at SLAC, corresponding to an integrated luminosity of 431.0     fb − 1 . The search leverages the full reconstruction of the B − meson in ϒ ( 4 S ) → B + B − decays, accompanied by the reconstruction of a Λ c + , to infer the presence of ψ D . No significant signal is observed, and limits on the B + → Λ c + ψ D branching fraction are set at the level of 1.6 × 10 − 4 at 90% confidence level for 0.94 < m ψ D < 2.99     GeV . These results set strong constraints on the parameter space allowed by B -meson baryogenesis.