Search for the lepton-flavour violating decays B0 → K*0τ±μ∓

A bstract A first search for the lepton-flavour violating decays B 0 → K *0 τ ± μ ∓ is presented. The analysis is performed using a sample of proton-proton collision data, collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV between 2011 and 2018, corresponding to an integrated luminosity of 9 fb − 1 . No significant signal is observed, and upper limits on the branching fractions are determined to be B(B⁰→ K⁰τ⁺μ⁻)<1.0(1.2)× 10⁻⁵ B B 0 → K ∗ 0 τ + μ − < 1.0 1.2 × 10 − 5 and B(B⁰→ K⁰τ⁻μ⁺)<8.2(9.8)× 10⁻⁶ B B 0 → K ∗ 0 τ − μ + < 8.2 9.8 × 10 − 6 at the 90% (95%) confidence level.