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Tomonori Tanigawa

Publications and source records attributed to Tomonori Tanigawa.

11 recordsLinked to original sources
arXiv2005

Finite size effects on kaonic pasta structures

Non-uniform structures of mixed phases at the first-order phase transition to charged kaon condensation are studied using a density functional theory within the relativistic mean field model. Including electric field effects and applying the Gibbs conditions in a proper way, we numerically determine density profiles of nucleons, electrons and condensed kaons. Importance of charge screening effects is elucidated and thereby we show that the Maxwell construction is effectively justified. Surface effect is also studied to figure out its effect on the density profiles.

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arXiv2005

Nuclear pasta structures and the charge screening effect

Non uniform structures of the nucleon matter at subnuclear densities are numerically studied by means of the density functional theory with relativistic mean-fields coupled with the electric field. A particular role of the charge screening effects is demonstrated.

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arXiv2005

Nuclear pasta structures in neutron stars and the charge screening

Non-uniform structures of the nucleon matter are expected at subnuclear densities and above the nuclear density: they are called nuclear pastas and kaon pastas, respectively. We numerically study these phases by means of the density functional theory with relativistic mean-fields and the electric field; the electric field is properly taken into account. Our results demonstrate a particular role of the charge screening effects on these non-uniform structures.

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arXiv2004

^{1}S_{0} proton superfluidity in neutron star matter: Impact of bulk properties

We study the ^{1}S_{0} proton pairing gap in neutron star matter putting emphasis on influence of the Dirac effective mass and the proton fraction on the gap within the relativistic Hartree-Bogoliubov model. The gap equation is solved using the Bonn-B potential as a particle-particle channel interaction. It is found that the maximal pairing gap Δ_{max} is 1-2 MeV, which has a strong correlation with the Dirac effective mass. Hence we suggest that it serves as a guide to narrow down parameter sets of the relativistic effective field theory. Furthermore, the more slowly protons increase with density in the core region of neutron stars, the wider the superfluid range and the slightly lower the peak of the gap become.

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arXiv2004

Coulomb screening effect on the nuclear-pasta structure

Using the density functional theory (DFT) with the relativistic mean field (RMF) model, we study the non-uniform state of nuclear matter, ``nuclear pasta''. We self-consistently include the Coulomb interaction together with other interactions. It is found that the Coulomb screening effect is significant for each pasta structure but not for the bulk equation of state (EOS) of the nuclear pasta phase.

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arXiv2003

Kaon Condensation and the Non-Uniform Nuclear Matter

Non-uniform structures of nuclear matter are studied in a wide density-range. Using the density functional theory with a relativistic mean-field model, we examine non-uniform structures at sub-nuclear densities (nuclear ``pastas'') and at high densities, where kaon condensate is expected. We try to give a unified view about the change of the matter structure as density increases, carefully taking into account the Coulomb screening effects from the viewpoint of first-order phase transition.

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arXiv2003

Possibility of ΛΛpairing and its dependence on background density in relativistic Hartree-Bogoliubov model

We calculate a ΛΛpairing gap in binary mixed matter of nucleons and Λhyperons within the relativistic Hartree-Bogoliubov model. Lambda hyperons to be paired up are immersed in background nucleons in a normal state. The gap is calculated with a one-boson-exchange interaction obtained from a relativistic Lagrangian. It is found that at background density ρ_{N}=2.5ρ_{0} the ΛΛpairing gap is very small, and that denser background makes it rapidly suppressed. This result suggests a mechanism, specific to mixed matter dealt with relativistic models, of its dependence on the nucleon density. An effect of weaker ΛΛattraction on the gap is also examined in connection with revised information of the ΛΛinteraction.

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arXiv2000

Phenomenological construction of a relativistic nucleon-nucleon interaction for the superfluid gap equation in finite density systems

We construct phenomenologically a relativistic particle-particle channel interaction which suits the gap equation for nuclear matter. This is done by introducing a density-independent momentum-cutoff parameter to the relativistic mean field (Hartree and Hartree-Fock) models so as to reproduce the pairing properties obtained by the Bonn-B potential and not to change the saturation property. The interaction so obtained can be used for the Relativistic Hartree-Bogoliubov calculation, but some reservation is necessary for the Relativistic Hartree-Fock-Bogoliubov calculation.

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arXiv1999

Effect of Vector Meson Mass Decrease on Superfluidity in Nuclear Matter

$^1S_0$ pairing in nuclear matter is investigated by taking the hadron mass decrease into account via the ``In-Medium Bonn potential'' which was recently proposed by Rapp et al. The resulting gap is significantly reduced in comparison with the one obtained with the original Bonn-B potential and we ascertain that the meson mass decrease is mainly responsible for this reduction.

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arXiv1998

Effects of Meson Mass Decrease on Superfluidity in Nuclear Matter

We calculate the $^1S_0$ pairing gap in nuclear matter by adopting the "in-medium Bonn potential" proposed by Rapp et al. [e-print nucl-th/9706006], which takes into account the in-medium meson mass decrease, as the particle-particle interaction in the gap equation. The resulting gap is significantly reduced in comparison with the one obtained by adopting the original Bonn potential.

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