Investigating Physics Beyond the Standard Model via Semileptonic tau Decays

Abstract

We examine the rare decays τ− → π−η(′)ντ that are G-parity suppressed within the Standard Model and provide valuable insights into new physics through interactions beyond the SM. In this study, we used an effective field theory framework to investigate the sensitivity of various observables associated with these decays, incorporating interactions within the Standard Model fields up to six-dimensional operators, under the assumption of massless and left-handed neutrinos. Our findings indicate that the examined observables can effectively explain the underlying dynamics of these decays, showing significant sensitivity to scalar and tensor couplings. Upcoming experiments such as Belle II, LHCb upgrades, and future electron-positron colliders aim to investigate τ decays with high accuracy, potentially uncovering new physics beyond the Standard Model. IX