Chiral symmetry restoration in a dense medium is to some extent a consequence of the nuclear pion cloud. These pions induce a mixing of the axial and vector current contributions in the axial and ...vector correlators. We discuss their influence on hadron masses and investigate the signal produced by the remaining contribution associated with chiral symmetry restoration. Using the quark-meson coupling model we find that the latter is associated with the reduction of hadron masses.
Nucl.Phys.A601:349-379,1996 The quark-meson coupling model, based on a mean field description of
non-overlapping nucleon bags bound by the self-consistent exchange of $\sigma$,
$\omega$ and $\rho$ ...mesons, is extended to investigate the properties of finite
nuclei. Using the Born-Oppenheimer approximation to describe the interacting
quark-meson system, we derive the effective equation of motion for the nucleon,
as well as the self-consistent equations for the meson mean fields. The model
is first applied to nuclear matter, after which we show some initial results
for finite nuclei.
The hydropower Generation Division of Electricité de France presents some results of its follow up of reservoir silling up, including the major problems that are encountered. On site experiences will ...be exposed such as evacuation of alluvions during the ten yearly drawdowns for inspection and outside those emptying periods.
We present results on the electromagnetic and axial nucleon form factors using two degenerate flavors of twisted mass fermions on lattices of spatial size 2.1 fm and 2.7 fm and a lattice spacing of ...about 0.09 fm. We consider pion masses in the range of 260-470 MeV. We chirally extrapolate results on the nucleon axial ch arge, the isovector Dirac and Pauli root mean squared radii and magnetic moment to the physical point and co mpare to experiment.
The quark-meson coupling model, based on a mean field description of non-overlapping nucleon bags bound by the self-consistent exchange of \(\sigma\), \(\omega\) and \(\rho\) mesons, is extended to ...investigate the properties of finite nuclei. Using the Born-Oppenheimer approximation to describe the interacting quark-meson system, we derive the effective equation of motion for the nucleon, as well as the self-consistent equations for the meson mean fields. The model is first applied to nuclear matter, after which we show some initial results for finite nuclei.
We present results on the mass of the baryon octet and decuplet using two flavors of light dynamical twisted mass fermions. The strange quark mass is fixed to its physical value from the kaon sector ...in a partially quenched set up. Calculations are performed for light quark masses corresponding to a pion mass in the range 270-500 MeV and lattice sizes of 2.1 fm and 2.7 fm. We check for cut-off effects and isospin breaking by evaluating the baryon masses at two different lattice spacings. We carry out a chiral extrapolation for the octet baryons and discuss results for the Omega.
We present results on the mass of the nucleon and the Delta using two dynamical degenerate twisted mass quarks and the tree-level Symanzik improved gauge action. The evaluation is performed at four ...quark masses corresponding to a pion mass in the range of about 300-600 MeV on lattices of 2.1-2.7 fm. We check for cut-off effects by evaluating these baryon masses on lattices of spatial size 2.1 fm at beta=3.9 and beta=4.05 and on a lattice of 2.4 fm at beta=3.8. The values we find are compatible within our statistical errors. Lattice results are extrapolated to the physical limit using continuum chiral perturbation theory. Performing a combined fit to our lattice data at beta=3.9 and beta=4.05 we find a nucleon mass of 964\pm 28 (stat.) \pm 8 (syst.) MeV. The nucleon mass at the physical point provides an independent determination of the lattice spacing. Using heavy baryon chiral perturbation theory at O(p^3) we find a_{\beta=3.9}=0.0890\pm 0.0039(stat.) \pm 0.0014(syst.) fm, and a_{\beta=4.05}= 0.0691\pm 0.0034(stat.) \pm 0.0010(syst.) fm, in good agreement with the values determined from the pion decay constant. Isospin violating lattice artifacts in the Delta-system are found to be compatible with zero for the values of the lattice spacings used in this work. Performing a combined fit to our lattice data at beta=3.9 and beta=4.05 we find for the masses of the Delta^{++,-} and Delta^{+,0} 1316 \pm 60 (stat.) MeV and 1330 \pm 74 (stat.) MeV respectively. We confirm that in the continuum limit they are also degenerate.
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