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We discuss the constraints induced by the algebra of the Poincare generators on non-relativistic effective field theories. In the first part we derive some relations among the matching coefficients of the HQET (and NRQCD), which have been formerly obtained by use of reparametrization invariance. In the second part we obtain new constraints on the matching coefficients of pNRQCD.
The approach of nonrelativistic QCD(NRQCD) factorization was proposed to study inclusive production of a quarkonium. It is widely used and successful. However, a recent study of gluon fragmentation into a quarkonium at two-loop level shows that the f
We present a quenched lattice calculation for the lowest lying $b bar b g$-hybrid states in the framework of NRQCD using the leading order Hamiltonian up to ${cal O}(mv^2)$. We demonstrate the existence of a nearly degenerate rotational band of state
We study the transition of a heavy quark pair from octet to singlet color configurations at next-to-next-to-leading order (NNLO) in heavy quarkonium production. We show that the infrared singularities in this process are consistent with NRQCD factori
We discuss factorization in heavy quarkonium production in high energy collisions using NRQCD. Infrared divergences at NNLO are not matched by conventional NRQCD matrix elements. However, we show that gauge invariance and factorization require that c
We discuss heavy quarkonium production through parton fragmentation, including a review of arguments for the factorization of high-p_T particles into fragmentation functions for hadronic initial states. We investigate the further factorization of fra