BPS Walls and Junctions in SUSY Nonlinear Sigma Models

TL;DR

This paper explores BPS walls and junctions in four-dimensional ${ m extbf{N}=1}$ SUSY nonlinear sigma models, discovering new solutions connecting multiple vacua and analyzing the structure of moduli spaces and SUSY vacua.

Contribution

It introduces new BPS junction solutions for models with multiple chiral superfields and characterizes models with a single superfield having a moduli space of $S^1$ topology.

Findings

Found new BPS junction solutions connecting N vacua.

Identified models with a single superfield and $S^1$ moduli space supporting BPS walls.

Classified SUSY conditions as superpotential stationary points or Kähler metric singularities.

Abstract

BPS walls and junctions are studied in ${\cal N}=1$ SUSY nonlinear sigma models in four spacetime dimensions. New BPS junction solutions connecting N discrete vacua are found for nonlinear sigma models with several chiral scalar superfields. A nonlinear sigma model with a single chiral scalar superfield is also found which has a moduli space of the topology of $S^1$ and admits BPS walls and junctions connecting arbitrary points in moduli space. SUSY condition in nonlinear sigma models are classified either as stationary points of superpotential or singularities of the K\"ahler metric in field space. The total number of SUSY vacua is invariant under holomorphic field redefinitions if we count ``runaway vacua'' also.