Search for the Baryon Number and Lepton Number Violating Decays Τ^-→Λπ^- and Τ^-→Λ̅π^- at Belle II

We present a search for the baryon number B and lepton number L violating decays τ^- →Λπ^- and τ^- →Λ̅π^- produced from the e^+e^-→τ^+τ^- process, using a 364 fb^-1 data sample collected by the Belle II experiment at the SuperKEKB collider. No evidence of signal is found in either decay mode, which have |Δ(B-L)| equal to 2 and 0, respectively. Upper limits at 90% credibility level on the branching fractions of τ^- →Λπ^- and τ^- →Λ̅π^- are determined to be 4.7 × 10^-8 and 4.3 × 10^-8, respectively.