Relativistic hypernuclear compact stars with calibrated equations of state. (arXiv:2001.08036v1 [hep-ph])
<a href="http://arxiv.org/find/hep-ph/1/au:+Fortin_M/0/1/0/all/0/1">M. Fortin</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Raduta_A/0/1/0/all/0/1">A. R. Raduta</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Avancini_S/0/1/0/all/0/1">S. Avancini</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Providencia_C/0/1/0/all/0/1">C. Provid&#xea;ncia</a>

Within the covariant density functional theory of hypernuclear matter we
build a series of equations of state for hypernuclear compact stars, by
calibrating the coupling constants of the $Xi$-hyperon to the experimental
binding energy of the single-$Xi$ hypernuclei $^{15}_{Xi^-}$C and
$^{12}_{Xi^-}$Be. Coupling constants of the $Lambda$-hyperon to nucleons have
been calibrated on a vast collection of experimental data on single $Lambda$
hypernuclei in Fortin et al. 2017, 2018 and Provid^encia et al. 2019, and we
employ those values. Uncertainties on the couplings of the $Sigma$-hyperon to
nuclear matter, due to lack of experimental data, are accounted for by allowing
for a wide variation of the well depth of $Sigma$ at rest in symmetric
saturated nuclear matter. To account for uncertainties in the nucleonic sector
at densities much larger than the saturation density, a rich collection of
parameterizations is employed, some of them in agreement with existing
constraints from nuclear physics and astrophysics. Neutron star properties are
investigated with all these calibrated equations of state. The effects of the
presence of hyperons on the radius, on the tidal deformability, on the moment
of inertia, and on the nucleonic direct Urca process are discussed. The
sensitivity of the hyperonic direct Urca processes to uncertainties in the
nucleonic and hyperonic sectors is also addressed. It is shown that the
relative variations of the radius, tidal deformability and moment of inertia
from the values that characterize purely nucleonic stars are linearly
correlated with the strangeness fraction. The maximum radius deviation,
obtained for most massive neutron stars, are $approx 10%$. The reduction of
the maximum mass, triggered by nucleation of strangeness, is estimated at
$approx 15 – 20%$, out of which $5%$ comes from insufficient information on
the $Sigma$-hyperon interactions.

Within the covariant density functional theory of hypernuclear matter we
build a series of equations of state for hypernuclear compact stars, by
calibrating the coupling constants of the $Xi$-hyperon to the experimental
binding energy of the single-$Xi$ hypernuclei $^{15}_{Xi^-}$C and
$^{12}_{Xi^-}$Be. Coupling constants of the $Lambda$-hyperon to nucleons have
been calibrated on a vast collection of experimental data on single $Lambda$
hypernuclei in Fortin et al. 2017, 2018 and Provid^encia et al. 2019, and we
employ those values. Uncertainties on the couplings of the $Sigma$-hyperon to
nuclear matter, due to lack of experimental data, are accounted for by allowing
for a wide variation of the well depth of $Sigma$ at rest in symmetric
saturated nuclear matter. To account for uncertainties in the nucleonic sector
at densities much larger than the saturation density, a rich collection of
parameterizations is employed, some of them in agreement with existing
constraints from nuclear physics and astrophysics. Neutron star properties are
investigated with all these calibrated equations of state. The effects of the
presence of hyperons on the radius, on the tidal deformability, on the moment
of inertia, and on the nucleonic direct Urca process are discussed. The
sensitivity of the hyperonic direct Urca processes to uncertainties in the
nucleonic and hyperonic sectors is also addressed. It is shown that the
relative variations of the radius, tidal deformability and moment of inertia
from the values that characterize purely nucleonic stars are linearly
correlated with the strangeness fraction. The maximum radius deviation,
obtained for most massive neutron stars, are $approx 10%$. The reduction of
the maximum mass, triggered by nucleation of strangeness, is estimated at
$approx 15 – 20%$, out of which $5%$ comes from insufficient information on
the $Sigma$-hyperon interactions.

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