String Webs and 1/4 BPS Monopoles

TL;DR

This paper constructs and analyzes new 1/4 BPS states in N=4 SU(N_c) Super-Yang-Mills theory using string webs, revealing their stability, degeneracy, and spin content, and identifying conditions for their decay and massless limits.

Contribution

It introduces a method to construct and study 1/4 BPS states via supersymmetric string webs, including states with high spin and long multiplets, expanding understanding of BPS spectra.

Findings

Existence of many new 1/4 BPS states in SU(N_c) SYM.

Identification of curves of marginal stability for these states.

Prediction of states with arbitrarily high spin and their massless limits.

Abstract

We argue for the existence of many new 1/4 BPS states in N=4 SU(N_c) Super-Yang-Mills theory with N_c>=3, by constructing them from supersymmetric string webs whose external strings terminate on parallel D3-branes. The masses of the string webs are shown to agree with the BPS bound for the corresponding states in SYM. We identify the curves of marginal stability, at which these states decay into other BPS states. We find the bosonic and fermionic zero modes of the string webs, and thereby the degeneracy and spin content of some of the BPS states. States of arbitrarily high spin are predicted in this manner, all of which become massless at the conformal point. For N_c>=4 we find BPS states which transform in long multiplets, and are therefore not protected against becoming stable non-BPS states as moduli are varied. The mass of these extremal non-BPS states is constrained as they are connected to BPS states. Analogous geometric phenomena are anticipated.