Transversity Distribution and Its Extraction

We describe the extraction of the transversity distribution involving a global analysis of pion-pair production in deep-inelastic scattering and in proton-proton collisions with one transversely polarized proton. The extraction relies on di-hadron fragmentation functions, which are taken from the analysis of the corresponding pion-pair production in electron-positron annihilation. We discuss the impact of COMPASS pseudodata from a future measurement of deep-inelastic scattering on transversely polarized deuterons. We discuss the potential incompatibility with lattice about the tensor charge, which is an important ingredient in the exploration of possible signals of new physics.