Half-BPS cosmic string in N=2 supergravity in the presence of a dilaton

TL;DR

This paper constructs new half-BPS cosmic string solutions within N=2 supergravity, demonstrating how a geometric gauging naturally produces the Fayet-Iliopoulos term and exploring the properties of these strings with an axion-dilaton field.

Contribution

It introduces novel half-BPS cosmic string solutions in N=2 supergravity with a geometric origin for the Fayet-Iliopoulos term, extending understanding of string solutions in supergravity models.

Findings

Cosmic strings have the same energy per unit length despite different dilaton values.

The axion-dilaton field remains as a constant parameter in solutions.

Solutions are compatible with a truncation to N=1 supergravity.

Abstract

We construct new half-BPS cosmic string solutions in D=4 N=2 supergravity compatible with a consistent truncation to N=1 supergravity where they describe D-term cosmic strings. The constant Fayet-Iliopoulos term in the N=1 D-term is not put in by hand but is geometrically engineered by a gauging in the mother N=2 supergravity theory. The coupling of the N=2 vector multiplets is characterized by a cubic prepotential admitting an axion-dilaton field, a common property of many compactifications of string theory. The axion-dilaton field survives the truncation to N=1 supergravity. On the string configuration the BPS equations constrain the dilaton to be an arbitrary constant. All the cosmic string solutions with different values of the dilaton have the same energy per unit length but different lenght scales.