dorsal/arxiv
View SchemaChiral approach to nuclear matter: Role of two-pion exchange with virtual delta-isobar excitation
| Authors | S. Fritsch, N. Kaiser, W. Weise |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/0406038 |
| URL | https://arxiv.org/abs/nucl-th/0406038 |
| DOI | 10.1016/j.nuclphysa.2004.12.042 |
| Journal | Nucl.Phys. A750 (2005) 259-293 |
Abstract
We extend a recent three-loop calculation of nuclear matter in chiral perturbation theory by including the effects from two-pion exchange with single and double virtual $\Delta(1232)$-isobar excitation. Regularization dependent short-range contributions from pion-loops are encoded in a few NN-contact coupling constants. The empirical saturation point of isospin-symmetric nuclear matter, $\bar E_0 = -16 $MeV, $\rho_0 = 0.16 $fm$^{-3}$, can be well reproduced by adjusting the strength of a two-body term linear in density (and weakening an emerging three-body term quadratic in density). The nuclear matter compressibility comes out as $K = 304 $MeV. The real single-particle potential $U(p,k_{f0})$ is substantially improved by the inclusion of the chiral $\pi N\Delta$-dynamics: it grows now monotonically with the nucleon momentum $p$. The effective nucleon mass at the Fermi surface takes on a realistic value of $M^*(k_{f0})=0.88M$. As a consequence of these features, the critical temperature of the liquid-gas phase transition gets lowered to the value $T_c \simeq 15 $MeV. In this work we continue the complex-valued single-particle potential $U(p,k_f)+i W(p,k_f)$ into the region above the Fermi surface $p>k_f$. The effects of $2\pi$-exchange with virtual $\Delta$-excitation on the nuclear energy density functional are also investigated. The effective nucleon mass associated with the kinetic energy density is $\widetilde M^*(\rho_0)= 0.64M$. Furthermore, we find that the isospin properties of nuclear matter get significantly improved by including the chiral $\pi N\Delta$-dynamics.
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"abstract": "We extend a recent three-loop calculation of nuclear matter in chiral\nperturbation theory by including the effects from two-pion exchange with single\nand double virtual $\\Delta(1232)$-isobar excitation. Regularization dependent\nshort-range contributions from pion-loops are encoded in a few NN-contact\ncoupling constants. The empirical saturation point of isospin-symmetric nuclear\nmatter, $\\bar E_0 = -16 $MeV, $\\rho_0 = 0.16 $fm$^{-3}$, can be well reproduced\nby adjusting the strength of a two-body term linear in density (and weakening\nan emerging three-body term quadratic in density). The nuclear matter\ncompressibility comes out as $K = 304 $MeV. The real single-particle potential\n$U(p,k_{f0})$ is substantially improved by the inclusion of the chiral $\\pi\nN\\Delta$-dynamics: it grows now monotonically with the nucleon momentum $p$.\nThe effective nucleon mass at the Fermi surface takes on a realistic value of\n$M^*(k_{f0})=0.88M$. As a consequence of these features, the critical\ntemperature of the liquid-gas phase transition gets lowered to the value $T_c\n\\simeq 15 $MeV. In this work we continue the complex-valued single-particle\npotential $U(p,k_f)+i W(p,k_f)$ into the region above the Fermi surface\n$p\u003ek_f$. The effects of $2\\pi$-exchange with virtual $\\Delta$-excitation on the\nnuclear energy density functional are also investigated. The effective nucleon\nmass associated with the kinetic energy density is $\\widetilde M^*(\\rho_0)=\n0.64M$. Furthermore, we find that the isospin properties of nuclear matter get\nsignificantly improved by including the chiral $\\pi N\\Delta$-dynamics.",
"arxiv_id": "nucl-th/0406038",
"authors": [
"S. Fritsch",
"N. Kaiser",
"W. Weise"
],
"categories": [
"nucl-th"
],
"doi": "10.1016/j.nuclphysa.2004.12.042",
"journal_ref": "Nucl.Phys. A750 (2005) 259-293",
"title": "Chiral approach to nuclear matter: Role of two-pion exchange with virtual delta-isobar excitation",
"url": "https://arxiv.org/abs/nucl-th/0406038"
},
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