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arXiv · 2403.09373

Gravitational Waves in Chern-Simons-Gauss-Bonnet Gravity

Tatsuya Daniel·Leah Jenks·Stephon Alexander
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Abstract

It is known that the four-dimensional effective field theory arising from heterotic string theory is general relativity with both a Chern-Simons and Gauss-Bonnet term. We study the propagation of gravitational waves in this combination of Chern-Simons and Gauss-Bonnet gravity, both of which have an associated scalar field, the axion and the dilaton respectively, that are kinetically coupled. We review how the combination of dynamical Chern-Simons and Gauss-Bonnet gravities can arise from string theory as corrections to general relativity and show how the gravitational wave waveform is modified in such a theory. We compare our results to a novel framework recently introduced for parametrizing the parity-violating sector (Chern-Simons), and use that to guide our construction of a similar parametrization for the parity-conserving (Gauss-Bonnet) sector. In general, we find that the contributions from the parity-violating and parity-conserving sectors are similar. Moreover, the kinetic coupling between the axion and dilaton introduces an extra contribution to the parity-violating sector of the gravitational waves. Using our parametrization, we are able to comment on initial constraints for the theory parameters, including the time variations of the axion and dilaton.

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Tatsuya Daniel, Leah Jenks, Stephon Alexander. 2024-03-14. Gravitational Waves in Chern-Simons-Gauss-Bonnet Gravity. https://doi.org/10.1103/physrevd.109.124012

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