Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Double Beta Decay in pn-QRPA Model with Isospin and SU(4) Symmetry
  Constraints   The transition matrix elements for the $0^{+}\to 0^{+}$ double beta decays
are calculated for $^{48}Ca$, $^{76}Ge $, $^{82}Se$, $^{100}Mo$, $^{128}Te$ and
$^{130}Te$ nuclei, using a ${\delta}$-interaction. As a guide, to fix the
particle-particle interaction strengths, we exploit the fact that the missing
symmetries of the mean field approximation are restored in the random phase
approximation by the residual interaction. Thus, the T=1, S=0 and T=0, S=1
coupling strengths have been estimated by invoking the partial restoration of
the isospin and Wigner SU(4) symmetries, respectively. When this recipe is
strictly applied, the calculation is consistent with the experimental limit for
the $2\nu$ lifetime of $^{48}Ca$ and it also correctly reproduces the $2\nu$
lifetime of $^{82}Se$. In this way, however, the two-neutrino matrix elements
for the remaining nuclei are either underestimated (for $^{76}Ge$ and
$^{100}Mo$) or overestimated (for $^{128}Te$ and $^{130}Te$) approximately by a
factor of 3. With a comparatively small variation ($<10%$) of the spin-triplet
parameter, near the value suggested by the SU(4) symmetry, it is possible to
reproduce the measured $T_{1/2}^{2\nu}$ in all the cases. The upper limit for
the effective neutrino mass, as obtained from the theoretical estimates of
$0\nu$ matrix elements, is $<m_{\nu}>\cong 1$ eV. The dependence of the nuclear
matrix elements on the size of the configuration space has been also analyzed.

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The categories of this paper are: econ
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The categories of this paper are: eess
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: math-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: stat
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The categories of this paper are: q-bio
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th
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The categories of this paper are: funct-an
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The categories of this paper are: hep-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: alg-geom
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The categories of this paper are: chem-ph
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The categories of this paper are: patt-sol