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Towards singularity- and ghost-free theories of gravity
Tirthabir Biswas1, Erik Gerwick, Tomi Koivisto
1Physics Department, Loyola University, Campus Box 92, New Orleans, Louisiana 70118, USA.
Physical Review Letters
|March 10, 2012
Summary
We introduce a new class of ghost-free gravitational actions, including nonlocal theories with better ultraviolet behavior. These actions generalize f(R) models and recover Einstein
Area of Science:
- Theoretical physics
- Quantum gravity
- Cosmology
Background:
- Einstein's general relativity is the standard model for gravity.
- f(R) theories are a well-studied modification of general relativity.
- Ultraviolet (UV) and Infrared (IR) behaviors are crucial for quantum field theories.
Purpose of the Study:
- To present the most general covariant ghost-free gravitational action in a Minkowski vacuum.
- To explore nonlocal actions with improved UV behavior.
- To demonstrate the recovery of Einstein's general relativity in the IR limit.
Main Methods:
- Covariant formulation of gravitational actions.
- Analysis of ghost-free conditions.
- Investigation of ultraviolet and infrared limits of modified gravity theories.
Main Results:
- A general class of covariant ghost-free gravitational actions is derived.
- This class includes nonlocal actions beyond standard f(R) models.
- The derived actions exhibit improved UV behavior and recover general relativity in the IR.
Conclusions:
- The presented framework offers a broader perspective on modified gravity.
- Nonlocal gravitational actions can be ghost-free and consistent.
- These findings have implications for quantum gravity and cosmology.
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