Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 1S-2S Spectrum of a Hydrogen Bose-Einstein Condensate   We calculate the two-photon 1S-2S spectrum of an atomic hydrogen
Bose-Einstein condensate in the regime where the cold collision frequency shift
dominates the lineshape. WKB and static phase approximations are made to find
the intensities for transitions from the condensate to motional eigenstates for
2S atoms. The excited state wave functions are found using a mean field
potential which includes the effects of collisions with condensate atoms.
Results agree well with experimental data. This formalism can be used to find
condensate spectra for a wide range of excitation schemes.

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The categories of this paper are: patt-sol
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The categories of this paper are: hep-th
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The categories of this paper are: q-fin
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The categories of this paper are: eess
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: ao-sci
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The categories of this paper are: q-bio
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The categories of this paper are: acc-phys
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The categories of this paper are: chem-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-ph
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The categories of this paper are: solv-int
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The categories of this paper are: plasm-ph
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con