Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pair term in the Electromagnetic Current within the Front-Form Dynamics:
  Spin-0 Case   The frame and scale dependence of the pair-term contribution to the
electromagnetic form factor of a spin-zero composite system of two-fermions is
studied within the Light Front. The form factor is evaluated from the
plus-component of the current in the Breit frame, using for the first time a
nonconstant, symmetric ansatz for the Bethe-Salpeter amplitude. The frame
dependence is analyzed by allowing a nonvanishing plus component of the
momentum transfer, while the dynamical scale is set by the masses of the
constituents and by mass and size of the composite system. A transverse
momentum distribution, associated with the Bethe-Salpeter amplitude, is
introduced which allows to define strongly and weakly relativistic systems. In
particular, for strongly relativistic systems, the pair term vanishes for the
Drell-Yan condition, while is dominant for momentum transfer along the
light-front direction. For a weakly relativistic system, fitted to the deuteron
scale, the pair term is negligible up to momentum transfers of 1(GeV/c)$^2$. A
comparison with results obtained within the Front-Form Hamiltonian dynamics
with a fixed number of constituents is also presented.

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The categories of this paper are: alg-geom
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th
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The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: patt-sol
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The categories of this paper are: econ
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The categories of this paper are: q-bio
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The categories of this paper are: cs
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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int