Between 1999 and 2010, the Belle experiment, located at KEK in Tsukuba, Japan, took e+e- annihilation data mostly near the Upsilon(4S) resonance. Due to the size of the dataset, Belle sampled a record breaking 1ab-1 delivered by the B-factory KEK-B, as well as the precision instrumentation and PID capabilities, this dataset represents a milestone for our studies of non-perturbative QCD effects in hadronization.

One focus of the Belle program is the precision measurement of Parton Fragmentation Functions, which parametrize non-perturbative hadronization effects in QCD factorization formulas if final state hadrons are detected in semi-inclusive measurements, e.g. in deep inelastic scattering or proton-proton collisions.

In particular, Belle results sensitive to transverse polarization dependent fragmentation functions, which can serve as ‘quark polarimeters’, play a crucial role in our understanding of the transverse spin structure of the nucleon. Beyond determining Fragmentation Functions, the study of hadronization allows us access to perturbative and non-perturbative QCD effects, which is complimentary to using the nucleon as our QCD laboratory.

This talk will present the latest results from th ongoing program of hadronization studies at Belle. I will also give an outlook towards related physics opportunities at Belle II, which will start data taking next year, sampling about 40 times the luminosity that Belle did.