The algebraic structure of Dyson--Schwinger equations with multiple insertion places
Nicholas Olson-Harris, Karen Yeats
TL;DR
This work develops a rigorous algebraic and combinatorial framework for Dyson--Schwinger equations with multiple insertion places by leveraging tubings of decorated rooted trees within the Connes--Kreimer Hopf algebra. It systematically builds from the CK Hopf algebra and Faà di Bruno theory to connect the renormalization group equation with the Riordan group, and then to Dyson--Schwinger equations via 1-cocycles and Mellin transforms. The main advance is a tubing-based expansion that yields explicit, combinatorially indexed series solutions for both single and multi-edge insertion DSEs, together with a generalized invariant-charge construction and RG PDEs that govern their scale dependence. The authors establish how to reduce to ordinary DSEs in some regimes, disprove a conjecture on universal linear substitutions, and provide a comprehensive tensor-power generalization that handles distinguished insertion places. These results deepen the algebraic understanding of renormalization, offer concrete combinatorial tools for studying perturbative and nonperturbative properties, and connect to broader structures such as regularity frameworks and resurgence.
Abstract
We give combinatorially controlled series solutions to Dyson--Schwinger equations with multiple insertion places using tubings of rooted trees and investigate the algebraic relation between such solutions and the renormalization group equation.
