  In 2010 the proton charge radius was extracted for the first time from muonic
hydrogen, a bound state of a muon and a proton. The value obtained was five
standard deviations away from the regular hydrogen extraction. Taken at face
value, this might be an indication of a new force in nature coupling to muons,
but not to electrons. It also forces us to reexamine our understanding of the
structure of the proton. Here I describe an ongoing theoretical research effort
that seeks to address this "proton radius puzzle". In particular, I will
present the development of new effective field theoretical tools that seek to
directly connect muonic hydrogen and muon-proton scattering.
