On non-linear superfield versions of the vector-tensor multiplet

TL;DR

This paper develops a harmonic superspace framework for non-linear N=2 vector-tensor multiplets, revealing two inequivalent versions and exploring their dualizations, constraints, and couplings to background gauge fields.

Contribution

It introduces a novel harmonic superspace description of non-linear vector-tensor multiplets, identifying a new version with a non-linear vector constraint and analyzing their dualities and couplings.

Findings

Two inequivalent non-linear vector-tensor multiplet versions identified.

Dualization procedures yield specific Kähler potentials.

Coupling to abelian background gauge multiplet demonstrated.

Abstract

We propose a harmonic superspace description of the non-linear vector-tensor N=2 multiplet. We show that there exist two inequivalent version: the old one in which one of the vectors is the field-strength of a gauge two-form, and a new one in which this vector satisfies a non-linear constraint and cannot be expressed in terms of a potential. In this the new version resembles the non-linear N=2 multiplet. We perform the dualization of both non-linear versions and discuss the resulting K\"ahler potentials. Finally, we couple the non-linear vector-tensor multiplet to an abelian background gauge multiplet.