Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Covariant RPA in Effective Hadronic Field Theory   In an effective hadronic theory constructed to describe long-range nuclear
physics, the dynamics of the vacuum can be expanded in terms with zero or a
finite number of derivatives acting on the fields. Thus vacuum dynamics can
always be absorbed in the (infinite number of) counterterm parameters
necessarily present in the effective lagrangian. These finite parameters, which
at present must be fitted to data, encode the empirical vacuum physics as well
as other short-range dynamics into the effective lagrangian; in practice, only
a small number of parameters must be fitted. The strength of the effective
field theory (EFT) framework is that there is no need to make a concrete
picture of the vacuum dynamics, as one does in a renormalizable hadronic
theory. At the one-loop level, the most convenient renormalization scheme
requires explicit sums over long-range (``valence'') nucleon orbitals only,
thus explaining the so-called ``no-sea approximation'' used in successful
covariant mean-field theory (MFT) calculations of static ground states. When
excited states are studied in the random-phase approximation (RPA), the same
EFT scheme dictates the inclusion of both familiar particle-hole pairs and
contributions that mix valence and negative-energy single-particle Dirac wave
functions. The modern EFT strategy therefore justifies and explains the
omission of some explicit contributions from the negative-energy Dirac sea of
nucleons, as was done to maintain conservation laws in earlier pragmatic
calculations of the nuclear linear response.

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The categories of this paper are: math
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
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The categories of this paper are: cs
28
The categories of this paper are: alg-geom
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The categories of this paper are: astro-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
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The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: hep-lat
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The categories of this paper are: cond-mat
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The categories of this paper are: math-ph
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The categories of this paper are: physics
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The categories of this paper are: patt-sol