تقرير
Stability of nonsingular cosmologies in Galileon models with torsion. A no-go theorem for eternal subluminality
| العنوان: | Stability of nonsingular cosmologies in Galileon models with torsion. A no-go theorem for eternal subluminality |
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| المؤلفون: | Mironov, S., Valencia-Villegas, M. |
| المصدر: | Phys. Rev. D, 109, 2024, 044-073 |
| سنة النشر: | 2023 |
| المجموعة: | General Relativity and Quantum Cosmology High Energy Physics - Theory |
| مصطلحات موضوعية: | High Energy Physics - Theory, General Relativity and Quantum Cosmology |
| الوصف: | Generic models in Galileons or Horndeski theory do not have cosmological solutions that are free of instabilities and singularities in the entire time of evolution. We extend this No-Go theorem to a spacetime with torsion. On this more general geometry the No-Go argument now holds provided the additional hypothesis that the graviton is also subluminal throughout the entire evolution. Thus, critically different for Galileons' stability on a torsionful spacetime, an arguably unphysical although arbitrarily short (deep UV) phase occurring at an arbitrary time, when the speed of gravity $(c_g)$ is slightly higher than luminal $(c)$, and by at least an amount $c_g\geq \,\sqrt{2}\,c $, can lead to an all-time linearly stable and nonsingular cosmology. As a proof of principle we build a stable model for a cosmological bounce that is almost always subluminal, where the short-lived superluminal phase occurs before the bounce and that transits to General Relativity in the asymptotic past and future. Comment: 8 pages, 4 figures. Matches the version accepted for publication in PRD. Added clarifying comments in the proof of the No-Go, references added, results unchanged |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1103/PhysRevD.109.044073 |
| URL الوصول: | http://arxiv.org/abs/2307.06929 |
| رقم الأكسشن: | edsarx.2307.06929 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1103/PhysRevD.109.044073 |
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