  It is well known that semileptonic decays of light hadrons and nuclei can be
used not only to determine the CKM element V_ud with high accuracy, but also as
probes of physics beyond the Standard Model. In this talk I review recent works
that studied this within an Effective Field Theory framework, comparing the
sensitivity of different low-energy and LHC observables. A clear
complementarity between low- and high-energy searches it is found.
