N ov 1 99 8 A heavy quark effective field lagrangian keeping particle and antiparticle mixed sectors ∗

A heavy quark effective field lagrangian keeping particle and antiparticle mixed sectors * Abstract We examine the applicability of the heavy-quark effective field theory (HQEFT) to heavy quark-antiquark pair annihilation or creation processes. To this end, we keep the particle-antiparticle sector in the inverse heavy-quark mass expansion of the HQEFT Lagrangian. We show that by removing the large mechanical momentum associated with both heavy quark and antiquark masses, it is sensible to use HQEFT in a certain kinematic domain. As a consequence, we discuss its application focusing mainly on heavy quarkonium production according to the color-octet mechanisms.