  We consider the role of precision measurements of beta decays and light meson
semi-leptonic decays in probing physics beyond the Standard Model in the LHC
era. We describe all low-energy charged-current processes within and beyond the
Standard Model using an effective field theory framework. We first discuss the
theoretical hadronic input which in these precision tests plays a crucial role
in setting the baseline for new physics searches. We then review the current
and upcoming constraints on the various non-standard operators from the study
of decay rates, spectra, and correlations in a broad array of light-quark
systems. We finally discuss the interplay with LHC searches, both within models
and in an effective theory approach. Our discussion illustrates the independent
yet complementary nature of precision beta decay measurements as probes of new
physics, showing them to be of continuing importance throughout the LHC era.
