Which sectors couple, and through which interaction. There is one wave — every line is \(\Psi_\infty\) coupling to itself on the coordinates the sectors share.
Electromagnetism and the weak coupling run through the \(d=2\) boson sector: a charged sector couples to the photon, and a fermion sector to the W and Z, in the \(d=2\) coordinates they share — not by a boson carried between two other sectors. Colour needs no boson sector (it is a kernel contact term), so it joins the two quark sectors directly. Gravity is the curvature of \(M_\infty\) and reaches every sector. Toggle a force to see exactly which sectors it links; click any node or line for detail.