Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Post-Minkowski action for point particles and a helically symmetric
  binary solution   Two Fokker actions and corresponding equations of motion are obtained for two
point particles in a post-Minkowski framework, in which the field of each
particle is given by the half-retarded + half-advanced solution to the
linearized Einstein equations. The first action is parametrization invariant,
the second a generalization of the affinely parametrized quadratic action for a
relativistic particle. Expressions for a conserved 4-momentum and angular
momentum tensor are obtained in terms of the particles' trajectories in this
post-Minkowski approximation. A formal solution to the equations of motion is
found for a binary system with circular orbits. For a bound system of this
kind, the post-Minkowski solution is a toy model that omits nonlinear terms of
relevant post-Newtonian order; and we also obtain a Fokker action that is
accurate to first post-Newtonian order, by adding to the post-Minkowski action
a term cubic in the particle masses. Curiously, the conserved energy and
angular momentum associated with the Fokker action are each finite and
well-defined for this bound 2-particle system despite the fact that the total
energy and angular momentum of the radiation field diverge. Corresponding
solutions and conserved quantities are found for two scalar charges (for
electromagnetic charges we exhibit the solution found by Schild). For a broad
class of parametrization-invariant Fokker actions and for the affinely
parametrized action, binary systems with circular orbits satisfy the relation
$dE = \Omega dL$ (a form of the first law of thermodynamics), relating the
energy, angular velocity and angular momentum of nearby equilibrium
configurations.

37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
18
The categories of this paper are: econ