Semi-local cosmic strings and the cosmological constant problem
We study the cosmological constant problem in a three-dimensional N = 2 supergravity theory with gauge group SU (2)<sub>global</sub> × U (1)<sub>local</sub>. The model we consider is known to admit string-like configurations, the so-called semi-local cosmic strings. We show t...
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| Formato: | Articulo |
| Lenguaje: | Inglés |
| Publicado: |
1997
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| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/122981 https://www.sciencedirect.com/science/article/abs/pii/S0370269396013858?via%3Dihub |
| Aporte de: |
| Sumario: | We study the cosmological constant problem in a three-dimensional N = 2 supergravity theory with gauge group SU (2)<sub>global</sub> × U (1)<sub>local</sub>. 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 solitonic 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 Bogomol'nyi bound, as a consequence of an Aharonov-Bohmlike 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. |
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