On the continuity of the commutative limit of the 4d N=4 non-commutative super Yang-Mills theory

TL;DR

This paper proves that the commutative limit of non-commutative 4d N=4 super Yang-Mills theory remains continuous in perturbation theory, despite UV/IR mixing effects, by demonstrating uniform convergence of Feynman integrals.

Contribution

It provides a rigorous proof that the commutative limit of non-commutative N=4 SYM is smooth at all orders, addressing UV/IR mixing issues.

Findings

UV effects do not break the commutative limit continuity

Uniform convergence of momentum integrals is established

The proof applies to all perturbative contributions, including non-planar diagrams

Abstract

We study the commutative limit of the non-commutative maximally supersymmetric Yang-Mills theory in four dimensions (N=4 SYM). The commutative limits of non-commutative spaces are important in particular in the applications of non-commutative spaces for regularisation of supersymmetric theories (such as the use of non-commutative spaces as alternatives to lattices for supersymmetric gauge theories and interpretations of some matrix models as regularised supermembrane or superstring theories), which in turn can play a prominent role in the study of quantum gravity via the gauge/gravity duality. In general, the commutative limits are known to be singular and non-smooth due to UV/IR mixing effects. We give a direct proof that UV effects do not break the continuity of the commutative limit of the non-commutative N=4 SYM to all order in perturbation theory, including non-planar contributions. This is achieved by establishing the uniform convergence (with respect to the non-commutative parameter) of momentum integrals associated with all Feynman diagrams appearing in the theory, using the same tools involved in the proof of finiteness of the commutative N=4 SYM.