Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nucleosynthesis of heavy elements in gamma ray bursts   The ultrarelativistic jets responsible for prompt and afterglow emission in
gamma ray bursts are presumably driven by a central engine that consists of a
dense accretion disk around a spinning black hole. We consider such engine,
composed of free nucleons, electron-positron pairs, Helium nuclei, and cooled
by neutrino emission. A significant number density of neutrons in the disk
provide conditions for neutron rich plasma in the outflows and jets. Heavy
nuclei are also formed in the accretion flow, at the distances 150-250
gravitational radii from the black hole. We study the process of
nucleosynthesis in the GRB engine, depending on its physical properties. Our
results may have important observational implications for the jet deceleration
process and heavy elements observed in the spectra of GRB afterglows.

26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
16
The categories of this paper are: stat
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int