In
theoretical physics, the
renormalization group (
RG) refers to a mathematical apparatus that allows systematic investigation of the changes of a physical system as viewed at different
distance scales. In particle physics, it reflects the changes in the underlying force laws (codified in a
quantum field theory) as the
energy scale at which physical processes occur varies, energy/momentum and resolution distance scales being effectively conjugate under the
uncertainty principle (cf.
Compton wavelength).