Donaldson-Witten Functions of Massless N=2 Supersymmetric QCD

TL;DR

This paper investigates the Donaldson-Witten invariants derived from N=2 supersymmetric SU(2) gauge theories with fewer than four massless hypermultiplets, revealing properties akin to generalized simple type four-manifolds.

Contribution

It analyzes the structure of Donaldson-Witten functions in massless N=2 SQCD with N_f=2,3, highlighting the role of strong-coupling singularities and their impact on four-manifold invariants.

Findings

Invariants associated with multiple massless monopoles show properties similar to generalized simple type four-manifolds.

Strong-coupling singularities influence the structure of Donaldson-Witten invariants.

The moduli space features singularities that affect the topological invariants of four-manifolds.

Abstract

We study the Donaldson-Witten function in four-dimensional topological gauge theory which is constructed from N=2 supersymmetric SU(2) gauge theory with $N_f < 4$ massless fundamental hypermultiplets. When $N_f = 2,3$, the strong-coupling singularities with multiple massless monopoles appear in the moduli space (the u-plane) of the Coulomb branch. We show that the invariants made out of such singularities exhibit a property which is similar to the one expected for four-manifolds of generalized simple type.