Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Radiative processes in external gravitational fields   Kinematically forbidden processes may be allowed in the presence of external
gravitational fields. These ca be taken into account by introducing generalized
particle momenta. The corresponding transition probabilities can then be
calculated to all orders in the metric deviation from the field-free
expressions by simply replacing the particle momenta with their generalized
counterparts. The procedure applies to particles of any spin and to any
gravitational fields. transition probabilities, emission power, and spectra
are, to leading order, linear in the metric deviation. It is also shown how a
small dissipation term in the particle wave equations can trigger a strong
backreaction that introduces resonances in the radiative process and deeply
affects the resulting gravitational background.

23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci