Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two particles on a star graph I   We consider a two particle system on a star graph with $\delta$-function
interaction. A class of eigensolutions is described which are constructed from
appropriate one particle solutions, and hence are parametrised by two momenta.
These solutions include a family of solutions with discontinuous derivative on
the diagonal.

13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom