Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theta Dependence of Meson Masses in the Small Mass Limit of the Massive
  Schwinger Model   We present a continuum formulation for $\theta$-vacua in the massive
Schwinger model on the light-front, where $\theta$ enters as a background
electric field. The effective coupling of the external field is partially
screened due to vacuum polarization processes. For small fermion masses and
small $\theta$ we calculate the mass of the meson and find agreement with
results from bosonization.

17
The categories of this paper are: q-fin
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The categories of this paper are: acc-phys
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The categories of this paper are: stat
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: cmp-lg
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The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex