Semi-local Cosmic Strings and the Cosmological Constant Problem

Abstract

We study the cosmological constant problem in a three-dimensional N=2 supergravity theory with gauge group SU[2]_{global}xU[1]_{local}. The model we consider is known to admit string-like configurations, the so-called semi-local cosmic strings. We show that the stability of these solutions is provided by supersymmetry through the existence of a lower bound for the energy, even though the manifold of the Higgs vacuum does not contain non-contractible loops. Charged Killing spinors do exist over configurations that saturate the Bogomolnyi bound, as a consequence of an Aharonov-Bohm-like effect. Nevertheless, there are no physical fermionic zero modes on these backgrounds. The exact vanishing of the cosmological constant does not imply, then, Bose-Fermi degeneracy. This provides a non-trivial example of the recent claim made by Witten on the vanishing of the cosmological constant in three dimensions without unphysical degeneracies.

12 pages, LaTeX. To appear in Physics Letters B

References in corpus (5)

• Strong Coupling and the Cosmological Constant
• Supergravity and a Bogomol'nyi Bound in Three Dimensions
• Bogomol'nyi Bounds and Killing Spinors in d=3 Supergravity
• S-Duality and Cosmological Constant in String Theory
• Conical Singularities in Three or Four-Dimensions and Supersymmetry Breaking

Cited by in corpus (8)

• Categorizing Different Approaches to the Cosmological Constant Problem
• D3/D7 Brane Inflation and Semilocal Strings
• D-term cosmic strings from N=2 Supergravity
• Chern-Simons Vortices in Supergravity
• Supersymmetric Electroweak Cosmic Strings
• Symmetric Variations of the Metric and Extrema of the Action for Pure Gravity
• Half-BPS cosmic string in N=2 supergravity in the presence of a dilaton
• Self-dual solitons in N=2 supersymmetric semilocal Chern-Simons theory