Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Explanation of 100-fold reduction of spectral shifts for hydrogen on
  helium films   We show that helium film-mediated hydrogen-hydrogen interactions account for
a two orders of magnitude discrepancy between previous theory and recent
experiments on cold collision shifts in spin-polarized hydrogen adsorbed on a
helium film. These attractive interactions also explain the anomalous
dependence of the cold collision frequency shifts on the $^3$He covering of the
film. Our findings suggest that the gas will become mechanically unstable
before reaching the Kosterlitz-Thouless transition unless the experiment is
performed in a drastically different regime, for example with a much different
helium film geometry.

35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol