Searches for LFV and LNV Decays at LHCb

The paper presents the latest progress on the searches for Lepton Number Violating (LNV) B Meson decays, the Lepton Flavour Violating (LFV) decay τ − → µ−µ−µ+, and the Lepton and Baryon Number Violating (LNV and BNV) decays τ − → µ+µ−p and τ − → µ−µ−p at the LHCb. These searches have been performed at a hadron collider for the first time. In the absence of signal we put upper limits, which are as follows: B(τ − → µ−µ−µ+) < 6.3 × 10−8, B(τ − → µ−µ+p) < 3.4 × 10−7, B(τ − → µ−µ−p) < 4.4 × 10−7 at 90 % CL. Inclusion of charged conjugate processes are implied throughout this document.