Effective Field Theory for Ultrasoft Momenta in NRQCD and NRQED

Abstract

We propose an effective field theory for heavy quark-antiquark bound states once the soft gluons have been integrated out. We also give new results for the matching between QCD (QED) and NRQCD (NRQED).

Comments: 5 pages, LaTeX, requires espcrc2.sty file. To appear in the proceedings of the QCD'97 conference, Montpellier, 3-9 July, 1997. Some typos in formulas corrected. One sentence changed