Cosmic R-string, R-tube and Vacuum Instability

TL;DR

This paper investigates cosmic R-strings arising from spontaneous U(1)_R symmetry breaking, revealing constraints on supersymmetric models and exploring conditions under which these strings are stable or metastable, with implications for vacuum decay and observable signatures.

Contribution

It introduces the concept of metastable R-strings that do not rapidly expand, and presents novel solutions like the 'bamboo' structure, linking string properties to vacuum structure.

Findings

Metastable R-strings can avoid rapid expansion.

Existence of 'bamboo'-like solutions indicating degenerate vacua.

Potential to infer true vacuum properties from string shape.

Abstract

We show that a cosmic string associated with spontaneous $U(1)_R$ symmetry breaking gives a constraint for supersymmetric model building. In some models, the string can be viewed as a tube-like domain wall with a winding number interpolating a false vacuum and a true vacuum. Such string causes inhomogeneous decay of the false vacuum to the true vacuum via rapid expansion of the radius of the tube and hence its formation would be inconsistent with the present Universe. However, we demonstrate that there exist metastable solutions which do not expand rapidly. Furthermore, when the true vacua are degenerate, the structure inside the tube becomes involved. As an example, we show a "bamboo"-like solution, which suggests a possibility observing an information of true vacua from outside of the tube through the shape and the tension of the tube.