In this short talk, we discuss chiral-odd PDFs that can be accessed through dihadron observables: the transversity PDF and the twist-3 scalar PDF e(x).
The former is subject to positivity constraints, the Soffer bound. Recent analyses have explored the role of theoretical constraints on the tensor charge. We comment on that point, in view of future improvements in all global analyses.
As for the scalar PDF, its extended relation to nonperturbative manifestations of QCD makes it a unique object. We discuss its first extraction in a collinear framework as well as possible and necessary extensions towards a full QCD analysis.