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General second-order scalar-tensor theory and self-tuning
Christos Charmousis1, Edmund J Copeland, Antonio Padilla
1LPT, CNRS UMR 8627, Université Paris Sud-11, 91405 Orsay Cedex, France.
Physical Review Letters
|March 10, 2012
Summary
We identified a unique scalar-tensor theory action enabling consistent self-tuning of the cosmological constant on cosmological backgrounds. This approach evades the Weinberg no-go theorem by breaking Poincaré invariance, allowing for novel cosmological solutions.
Area of Science:
- Theoretical physics
- Cosmology
- Gravitation
Background:
- Scalar-tensor theories are extensions of Einstein's general relativity.
- Cosmological constant problem and the Weinberg no-go theorem pose challenges.
- Friedmann-Lemaître-Robertson-Walker (FLRW) backgrounds describe a homogeneous and isotropic universe.
Purpose of the Study:
- To establish a unique action for a consistent self-tuning mechanism in scalar-tensor gravity.
- To investigate the evasion of the Weinberg no-go theorem in cosmological settings.
- To explore the potential for nontrivial cosmological solutions.
Main Methods:
- Formulation of the most general scalar-tensor theory with second-order field equations.
- Identification of a unique action composed of four base Lagrangians.
- Analysis of scalar field's role in breaking Poincaré invariance on self-tuning vacua.
Main Results:
- A unique action is established for self-tuning on FLRW backgrounds.
- The action combines four Lagrangians with specific geometric dependencies.
- Poincaré invariance breaking by the scalar field screens spacetime curvature from the cosmological constant.
Conclusions:
- The developed theory provides a consistent self-tuning mechanism for the cosmological constant.
- The framework evades the Weinberg no-go theorem, offering new avenues in cosmology.
- The structure of the theory allows for the generation of nontrivial cosmological solutions.
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