T. Mannel et Ga. Schuler, HQ(Q)OVER-BAR-ET - AN EFFECTIVE THEORY APPROACH TO HEAVY QUARKONIA DECAYS, Physics letters. Section B, 349(1-2), 1995, pp. 181-188
We discuss systems containing a heavy quark and a heavy antiquark in t
he infinite mass limit of QCD. Studying the limit of equal velocities
for both heavy particles, we formulate an effective theory approach to
heavy quarkonia-like systems. The method is well suited to processes
in which the two heavy quarks annihilate, such as electromagnetic and
strong decays of charmonium and bottomonium and weak decays of B-c.