Speaker
Description
Transverse Momentum Dependent (TMD) factorization leads to well established theorems for a restricted class of processes. In such cases, some of the effects produced by the soft radiation cancel out and the physics associated to them cannot be accessed. Extension of the factorization to non-standard processes inevitably leads to deal with the non trivial structure of the soft sector, revealing details that in the standard cases are not accessible. In particular, comparing the extraction of the TMD Fragmentation Function obtained from SIDIS with that extracted from single-inclusive $e^+e^-$ annihilation gives access to a new universal non-perturbative function describing the long-distance behavior of soft gluons and potentially revealing hidden properties of the QCD vacuum. In this talk, I present such comparison among the most recent phenomenological extractions and I will provide the first quantitative estimate of these hidden soft effects.