The nuclear symmetry energy from neutron skins and pure neutron matter in a Bayesian framework. (arXiv:2008.00042v1 [nucl-th])
<a href="http://arxiv.org/find/nucl-th/1/au:+Newton_W/0/1/0/all/0/1">William G. Newton</a>, <a href="http://arxiv.org/find/nucl-th/1/au:+Crocombe_G/0/1/0/all/0/1">Gabriel Crocombe</a>
We present an inference of the nuclear symmetry energy magnitude $J$, the
slope $L$ and the curvature $K_{rm sym}$ by combining neutron skin data on Ca,
Pb and Sn isotopes and our best theoretical information about pure neutron
matter (PNM). A Bayesian framework is used to consistently incorporate prior
knowledge of the PNM equation of state from chiral effective field theory
calculations. Neutron skins are modeled in a Hartree-Fock approach using an
extended Skyrme energy-density functional which allows for independent
variation of $J$, $L$ and $K_{rm sym}$ without affecting the symmetric nuclear
matter equation of state. We discuss the choice of neutron skin data sets, and
combining errors in quadrature we obtain 95% credible values of
$J=31.3substack{+4.2 \ -5.9}$ MeV, $L=40substack{+34 \ -26}$ MeV and
$K_{tau} = L – 6K_{rm sym}= -444substack{+100 \ -84}$ MeV using
uninformative priors in $J$, $L$ and $K_{rm sym}$, and $J=31.9substack{+1.3
\ -1.3}$ MeV, $L=37substack{+9 \ -8}$ MeV and $K_{tau} = -480substack{+25
\ -26}$ MeV using PNM priors. The correlations between symmetry energy
parameters induced by neutron skin data is discussed and compared with the
droplet model. Neutron skin data alone is shown to place limits on the symmetry
energy parameters as stringent as those obtained from chiral effective field
theory alone, and when combined the 95% credible intervals are reduced by a
factor of 4-5. Ahead of new measurements of lead and calcium neutron skins from
parity-violating electron scattering experiments at Jefferson Lab and Mainz
Superconducting Accelerator, we make predictions based on existing data on
neutron skins of tin for the neutron skins of calcium and lead of
0.166$pm$0.008 fm and $0.169 pm 0.014$ fm respectively, using uninformative
priors, and 0.167$pm$0.008 fm and $0.172 pm 0.015$ fm respectively, using PNM
priors.
We present an inference of the nuclear symmetry energy magnitude $J$, the
slope $L$ and the curvature $K_{rm sym}$ by combining neutron skin data on Ca,
Pb and Sn isotopes and our best theoretical information about pure neutron
matter (PNM). A Bayesian framework is used to consistently incorporate prior
knowledge of the PNM equation of state from chiral effective field theory
calculations. Neutron skins are modeled in a Hartree-Fock approach using an
extended Skyrme energy-density functional which allows for independent
variation of $J$, $L$ and $K_{rm sym}$ without affecting the symmetric nuclear
matter equation of state. We discuss the choice of neutron skin data sets, and
combining errors in quadrature we obtain 95% credible values of
$J=31.3substack{+4.2 \ -5.9}$ MeV, $L=40substack{+34 \ -26}$ MeV and
$K_{tau} = L – 6K_{rm sym}= -444substack{+100 \ -84}$ MeV using
uninformative priors in $J$, $L$ and $K_{rm sym}$, and $J=31.9substack{+1.3
\ -1.3}$ MeV, $L=37substack{+9 \ -8}$ MeV and $K_{tau} = -480substack{+25
\ -26}$ MeV using PNM priors. The correlations between symmetry energy
parameters induced by neutron skin data is discussed and compared with the
droplet model. Neutron skin data alone is shown to place limits on the symmetry
energy parameters as stringent as those obtained from chiral effective field
theory alone, and when combined the 95% credible intervals are reduced by a
factor of 4-5. Ahead of new measurements of lead and calcium neutron skins from
parity-violating electron scattering experiments at Jefferson Lab and Mainz
Superconducting Accelerator, we make predictions based on existing data on
neutron skins of tin for the neutron skins of calcium and lead of
0.166$pm$0.008 fm and $0.169 pm 0.014$ fm respectively, using uninformative
priors, and 0.167$pm$0.008 fm and $0.172 pm 0.015$ fm respectively, using PNM
priors.
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