Gauge invariant prescription to avoid a γ -crossing instability in a Galileon bounce

We revisit the evolutions of scalar perturbations in a nonsingular Galileon bounce. It is known that the second-order differential equation governing the perturbations is numerically unstable at a point called the γ-crossing. This instability is usually circumvented using certain gauge choices. We s...

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Bibliographic Details
Published in:Physical review. D 2019-05, Vol.99 (10), p.103517, Article 103517
Main Author: Raveendran, Rathul Nath
Format: Article
Language:English
Subjects:
Differential equations
Invariants
Stability
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Summary:We revisit the evolutions of scalar perturbations in a nonsingular Galileon bounce. It is known that the second-order differential equation governing the perturbations is numerically unstable at a point called the γ-crossing. This instability is usually circumvented using certain gauge choices. We show that the perturbations can be evolved across this point by solving the first-order differential equations governing suitable gauge-invariant quantities without any instabilities. We demonstrate this method in a matter bounce scenario described by the Galileon action.
ISSN:2470-0010
2470-0029
DOI:10.1103/PhysRevD.99.103517