Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New low temperature phase in dense hydrogen: The phase diagram to 421
  GPa   In the quest to make metallic hydrogen at low temperatures a rich number of
new phases have been found and the highest pressure ones have somewhat flat
phase lines, around room temperature. We have studied hydrogen to static
pressures of GPa in a diamond anvil cell and down to liquid helium
temperatures, using infrared spectroscopy. We report a new phase at a pressure
of GPa and T=5 K. Although we observe strong darkening of the sample in the
visible, we have no evidence that this phase is metallic hydrogen.

13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga