Discussion on the field and power definition in finite-size object scattering problem

Author(s):  
Junhong Wang ◽  
Zhan Zhang
2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Zhengwen Liu ◽  
Rafael A. Porto ◽  
Zixin Yang

Abstract Building upon the worldline effective field theory (EFT) formalism for spinning bodies developed for the Post-Newtonian regime, we generalize the EFT approach to Post-Minkowskian (PM) dynamics to include rotational degrees of freedom in a manifestly covariant framework. We introduce a systematic procedure to compute the total change in momentum and spin in the gravitational scattering of compact objects. For the special case of spins aligned with the orbital angular momentum, we show how to construct the radial action for elliptic-like orbits using the Boundary-to-Bound correspondence. As a paradigmatic example, we solve the scattering problem to next-to-leading PM order with linear and bilinear spin effects and arbitrary initial conditions, incorporating for the first time finite-size corrections. We obtain the aligned-spin radial action from the resulting scattering data, and derive the periastron advance and binding energy for circular orbits. We also provide the (square of the) center-of-mass momentum to $$ \mathcal{O}\left({G}^2\right) $$ O G 2 , which may be used to reconstruct a Hamiltonian. Our results are in perfect agreement with the existent literature, while at the same time extend the knowledge of the PM dynamics of compact binaries at quadratic order in spins.


1987 ◽  
Vol 77 (6) ◽  
pp. 2192-2211
Author(s):  
Vijay K. Varadan ◽  
Akhlesh Lakhtakia ◽  
Vasundara V. Varadan ◽  
Charles A. Langston

Abstract A method for determining for determining the elastodynamic (P and SV waves) radiation characteristics of finite-size sources buried in horizontally layered media, having periodically corrugated interfaces, is described. In particular, the example problem chosen to illustrate the procedure is as follows: a solid plate lies on top of a solid half-space; the solid-solid interface has been taken to be planar, but traction-free conditions prevail on the other boundary of the elastic plate, which surface is also periodically corrugated; and the source has been taken to be an isotropic, P-wave line source located inside the elastic plate. The technique presented utilizes the plane wave spectral decomposition of the relevant fields within the framework of the extended boundary condition method or the T matrix method. Since the T-matrix method is a matrix approach, it is very attractive computationally and is certainly more tractable than a method based on the direct solution of the integral equations involved in the scattering problem. Numerical results are given to delineate the various features of the field diffracted into the elastic half-space, as well as the displacement field induced on the traction-free boundary of the elastic plate. The specific example examined is directly related to regional wave propagation in a continental crustal wave guide.


1987 ◽  
Vol 109 (1) ◽  
pp. 69-74 ◽  
Author(s):  
A. Lakhtakia ◽  
V. K. Varadan ◽  
V. V. Varadan

We describe here a method for determining the elastodynamic (P and SV waves) radiation characteristics of finite-size sources buried in a horizontally layered medium, having periodically corrugated interfaces. The presented technique utilizes the planewave spectral decomposition of the relevant fields within the framework of the extended boundary condition method (EBCM). Since the EBCM is a matrix approach, it is very attractive computationally, and is certainly more tractable than a method based on the direct solution of the integral equations involved in the scattering problem. Several problems in such diverse areas as noise control, seismology, meteorology, and oceanography can be solved using the derived methodology.


1981 ◽  
Vol 64 (10) ◽  
pp. 1-8
Author(s):  
Tsuyoshi Matsuo ◽  
Yasumichi Hasegawa ◽  
Yoshikuni Okada

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