Radiative Corrections to Quarkonium Decays: From a Model to a Rigorous Theory

Most previous calculations of the annihilation decay rates of heavy quarkonium were based on factorization assumptions that were unproven and, in some cases, even incorrect. The recent development of a general factorization formula for heavy quarkonium annihilation rates has provided a rigorous theoretical foundation for such calculations. The factorization formula is based on the use of the effective field theory NRQCD to factor the decay rate into short-distance coefficients that can be calculated in perturbation theory and long-distance matrix elements that can be computed using lattice simulations. This approach allows annihilation decay rates to be computed entirely from first principles.