Speaker
Description
Perturbative instabilities at next-to-next-to-leading order (NNLO) have become a recurring challenge in theoretical predictions for quarkonium production and decay within the NRQCD framework, often leading to large corrections, enhanced scale dependence, or even unphysical negative cross sections and decay widths. In this talk, I will present our recent work addressing the origin of these instabilities. By consistently incorporating the perturbative soft contributions to the quarkonium wave function at the origin, NNLO predictions exhibit improved perturbative convergence and become independent of the NRQCD factorization scale at this order. The proposed framework is applied to a wide range of S-wave color-singlet production and decay processes, yielding substantially improved agreement with experimental measurements and providing a robust foundation for future precision studies of heavy quarkonium.