Speaker
Description
Baryon number violation (BNV) provides one of the most sensitive probes of physics beyond the Standard Model. In this work, we investigate rare BNV tau decays induced by effective field theory (EFT) operators, including scenarios with associated dark-sector final states. We demonstrate that any framework generating BNV tau decays necessarily induces proton decay, leading to stringent constraints from existing experimental bounds on proton lifetime. As a result, we find that the branching ratios ($\mathcal{B}$) for $\tau$ decays even after involving dark-sector particles are highly suppressed, of order $\mathcal{O}(10^{-30})$, rendering their direct observation extremely challenging at current facilities such as Belle II. We further explore proton–tau mixing operators and analyze the resulting multi-body proton decay channels mediated by semi-leptonic tau decays. The obtained spectra of the final state charged pions from those processes indicate that one can still search for them in Super-K/ Hyper-K.