Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Positronium in a liquid phase: formation, bubble state and chemical
  reactions   This chapter reviews the following items: 1. Energy deposition and track
structure of fast positrons: ionization slowing down, number of ion-electron
pairs, typical sizes, thermalization, electrostatic interaction between e+ and
its blob, effect of local heating; 2. Positronium formation in condensed media:
the Ore model, quasifree Ps state, intratrack mechanism of Ps formation; 3.
Fast intratrack diffusion-controlled reactions: Ps oxidation and ortho-para
conversion by radiolytic products, reaction rate constants, interpretation of
the PAL spectra in water at different temperatures; 4. Ps bubble models.
"Non-point" positronium: wave function, energy contributions, relationship
between the pick-off annihilation rate and the bubble radius.

10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
21
The categories of this paper are: adap-org