Speaker
Description
We report progress on the determination and study of quarkonium formation within the fragmentation approximation. Our analyses address the moderate and large transverse-momentum regime, where the production mechanism based on the collinear fragmentation from a single parton is expected to prevail over the short-distance emission, directly from the hard-scattering subprocess, of the constituent heavy-quark pair. We rely on Non-Relativistic-QCD (NRQCD) next-to-leading calculations for all the parton fragmentation channels to vector ($J/\psi$ and $\Upsilon$) and pseudoscalar ($\eta_c$ and $\eta_b$) quarkonia, which we take as proxies for initial-scale inputs. Thus, a complete set of variable-flavor number-scheme fragmentation functions, named NRFF1.0, are built through standard DGLAP evolution. Statistical errors are assessed via a Monte Carlo, replica-like approach that also accounts for Missing Higher-Order Uncertainties (MHOUs). The link between the NRFF1.0 approach and the MCscales one will be discussed. By starting from recent phenomenological results in the high-energy QCD sector, we trace a path towards novel studies aimed at unveiling the connection between the collinear factorization and the non-relativistic effective theory.
