Muon capture in hydrogen

Muon capture in hydrogen is a basic charged-current electroweak process. Historically, it played an essential role in establishing the structure of the weak interactions. More recently, the connection between nucleon and even few-nucleon observables at low energies and fundamental QCD has been elucidated within effective field theories. Muon capture experiments test the underlying QCD symmetries and will serve as a calibration of important astrophysical neutrino reactions. The current programme of high precision experiments is described.