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New post-Newtonian parameter to test Chern-Simons gravity
Stephon Alexander1, Nicolas Yunes
1Institute for Gravitational Physics and Geometry, Center for Gravitational Wave Physics and Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Physical Review Letters
|February 1, 2008
Summary
Chern-Simons gravity matches general relativity's PPN parameters but adds a new term. This term modifies frame dragging and gyroscopic precession, offering experimental tests for string theory.
Area of Science:
- Theoretical physics
- Gravitational physics
- String theory
Background:
- The parametrized post-Newtonian (PPN) framework is crucial for testing alternative theories of gravity.
- Chern-Simons (CS) gravity presents a potential modification to Einstein's general relativity.
- Understanding deviations from general relativity is key to exploring fundamental physics.
Purpose of the Study:
- To analyze Chern-Simons gravity within the PPN framework.
- To identify and quantify potential deviations from general relativity predicted by CS gravity.
- To explore experimental avenues for testing CS gravity and string theory.
Main Methods:
- Derivation of a weak-field solution for the modified field equations of CS gravity.
- Comparison of the resulting PPN parameters with those of general relativity.
- Estimation of the magnitude of the newly introduced term in CS gravity.
Main Results:
- CS gravity shares PPN parameters with general relativity.
- A novel term, dependent on the CS coupling and the curl of the PPN vector potential, is identified.
- This new term induces modifications to frame dragging and gyroscopic precession.
Conclusions:
- CS gravity introduces unique, testable predictions distinct from general relativity.
- Experimental measurements, such as those from Gravity Probe B, can constrain CS gravity.
- These constraints can provide indirect tests of string theory models incorporating CS terms.
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