Effective field theory and gravitational waves from compact binary coalesence
Effective field theory is a powerful framework for building an understanding of apparently complicated physical problems and for making (approximate) predictions. One example for such a problem is the coalesence of binaries containing black holes and/or neutron stars, described by the nonlinear theory of general relativity together with a theory of nuclear matter. The effective field theory framework leads to a natural description of the inspiral part of this coalesence, where the bodies are well separated. Approximate predictions for the dynamics and the emitted gravitational waves can be worked out by expanding in the separation. Effects of the bodies angular momentum (spin), their tidal deformation, and from a modification of gravity can be incorporated systematically. Feynman diagrams and integrals can be used as the main calculational tool, but recently powerful methods for the calculation of (quamtum gravity) scattering amplitudes are being adapted to the classical binary problem as well. Beside the inspiral phase of compact binary coalesence, the bodies undergo the merger and ringdown phases. Different approaches to combine knowledge of these three phases into inspiral-merger-ringdown waveform models are presented, with an emphasis on effective-one-body models.
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