Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effective Action and Thermodynamics of Radiating Shells in General
  Relativity   An effective action is obtained for the area and mass aspect of a thin shell
of radiating self-gravitating matter. On following a mini-superspace approach,
the geometry of the embedding space-time is not dynamical but fixed to be
either Minkowski or Schwarzschild inside the shell and Vaidya in the external
space filled with radiation. The Euler-Lagrange equations of motion are
discussed and shown to entail the expected invariance of the effective
Lagrangian under time-reparametrization. They are equivalent to the usual
junction equations and suggest a macroscopic quasi-static thermodynamic
description.

15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph