Speaker
Description
I discuss ongoing progress in the understanding of heavy-quark transverse momentum-dependent (TMD) fragmentation functions (FFs). These advances include their explicit next-to-leading order calculation in massive SCET and bHQET, exposing a rich singularity structure that is also relevant for the extension of fixed-order subtraction schemes to quasi-collinear limits. I further present how many independent nonperturbative bHQET functions are needed to fully characterize heavy-quark fragmentation in the transverse plane, accounting -- for the first time -- for arbitrary heavy hadron polarization. This analysis exposes powerful spin symmetry relations across all possible (polarized) TMD FFs. I close by discussing prospects for interpreting these novel bHQET matrix elements in the context of quantum information theory as applied to hadronization.