Partial breaking N=4 to N=2: hypermultiplet as a Goldstone superfield

TL;DR

This paper explores the partial breaking of supersymmetry from N=4 to N=2 using a hypermultiplet superfield as a Goldstone mode, linking it to super 5-brane dynamics in D=10.

Contribution

It introduces a non-linear realization approach where the hypermultiplet superfield acts as a Goldstone superfield for partial supersymmetry breaking.

Findings

Identifies the hypermultiplet superfield as the Goldstone superfield.

Derives worldvolume supersymmetric equations for the super 5-brane.

Suggests existence of off-shell hypermultiplet actions in harmonic superspace.

Abstract

We describe the partial breaking of $N=1 D=10$ supersymmetry down to $(1,0) d=6$ supersymmetry within the non-linear realization approach. The basic Goldstone superfield associated with this breaking is shown to be the $(1,0) d=6$ hypermultiplet superfield $q^{ia}$ subjected to a non-linear generalization of the standard hypermultiplet superfield constraint. The dynamical equations implied by this constraint are identified as the manifestly worldvolume supersymmetric equations of the Type I super 5-brane in D=10. We give arguments in favour of existence of an appropriate brane extension of off-shell hypermultiplet actions in harmonic superspace. Some related problems, in particular, the issue of utilizing other $(1,0) d=6$ supermultiplets as Goldstone ones, are shortly discussed.