Closing in on New Physics in light-quark flavour transitions: from tau decays to the LHC

ended

This action studies the synergy of the Energy and the Intensity Frontiers, with the focus on non-standard effects involving leptons and light quarks. The project starts with an unprecedented Effective-Field-Theory (EFT) analysis of hadronic tau decays including non-standard effects. Their discovery potential and complementarity with direct LHC searches will be assessed in a model-independent approach. The results will be combined with d(s)→u l nu (l=e,mu) transitions and eq → eq (q=u,d,s) processes in a comprehensive EFT flavour fit that will close in on New Physics involving leptons and light quarks. The obtained model-independent results will be particularised to specific New Physics scenarios that are of phenomenological or theoretical interest. Special attention will be paid to symmetries, symmetry-breaking patterns and classes of models with well-defined power-counting schemes. The emerging correlations between the studied observables will be analysed in detail. Finally, the EFT matching to a general Leptoquark parametrisation will be carried out, along with a phenomenological analysis. The implications for specific models proposed in the recent literature to accommodate various Standard Model tensions will be studied.