Heavy Quarkonium and Nonrelativistic Effective Field Theories

Abstract

We study some general aspects of the formalism of potential NRQCD (pNRQCD), an effective field theory that deals with ultrasoft degrees of freedom in Heavy Quarkonium systems. Specific attention is paid to its effective Lagrangian that it is displayed at the present level of accuracy.

Comments: 4 pages, LaTeX. Talk given at QCD Euroconference 99, Montpellier, 7-13 July 1999. Submitted to Nucl. Phys. Proc. Suppl. B