What is the relationship between pQCD and NRQCD? Is it that pQCD is for high energy/short-distance regime, e.g. quark gluon plasma? And NRQCD is for low energy/long-distance regime, e.g. quarkonium ? And what is relation between heavy quark effective theory and pQCD and that between heavy quark effective theory and NRQCD ? Thanks in advance.