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arXiv · 2410.24149

Global String Instantons

Jose J. Blanco-Pillado·Georgios Fanaras·Alexander Vilenkin
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Abstract

We study the formation of gravitating global strings through quantum mechanical tunneling. The instantons that describe the nucleation process are characterized by two parameters: the string core thickness and its gravitational backreaction controlled by the string core energy density. We obtain solutions across a wide range of these parameters by carrying out numerical integration via multiple shooting methods. Our results are in agreement with previous findings on the nucleation of other topological defects; specifically, after reaching a certain threshold for the string core thickness or its gravitational backreaction, the configuration becomes homogeneous in a manner akin to Hawking-Moss solutions. Additionally, we analyze the global structure of the analytical continuation of the solutions to Lorentzian signature, revealing the emergence of a region of spacetime that describes an anisotropic universe. Finally, we also discuss the relevance of these instantons in the context of quantum cosmology.

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Jose J. Blanco-Pillado, Georgios Fanaras, Alexander Vilenkin. 2024-10-31. Global String Instantons. https://arxiv.org/abs/2410.24149

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