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arXiv 1304.3175nucl-th
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手征核力的微观光学势

Microscopic optical potential from chiral nuclear forces

J. W. Holt, N. Kaiser, G. A. Miller, W. Weise

摘要:

从手征有效场论中的核相互作用出发,在无限大的同位旋对称核物质介质中,构造了与能量和密度相关的核子单粒子势.两核子力和三核子力的首阶项都对核子自能产生了真实的、与能量无关的贡献。从两个核子力的Hartree-Fock贡献是有吸引力的,强烈的动量依赖,相反,从三个核子力的贡献,提供了一个几乎恒定的排斥平均场,近似线性增长的核密度。总之,领先的订单微扰的贡献产生一个有吸引力的单粒子的潜力,但太弱相比,现象学。来自二体和三体力的二阶贡献提供了达到现象学深度所需的额外吸引力。光学势的虚部对于费米动量以下(以上)的动量为正(负),出现在二阶,并且当仅存在两个核子相互作用时,关于费米表面几乎是反转对称的。虚部是强吸收的,需要包括有效质量校正以及自洽的单粒子能量,以达到定性的协议与唯象。

英文摘要:

The energy- and density-dependent single-particle potential for nucleons is constructed in a medium of infinite isospin-symmetric nuclear matter starting from realistic nuclear interactions derived within the framework of chiral effective field theory. The leading-order terms from both two- and three-nucleon forces give rise to real, energy-independent contributions to the nucleon self-energy. The Hartree-Fock contribution from the two-nucleon force is attractive and strongly momentum dependent, in contrast to the contribution from the three-nucleon force which provides a nearly constant repulsive mean field that grows approximately linearly with the nuclear density. Together, the leading-order perturbative contributions yield an attractive single-particle potential that is however too weak compared to phenomenology. Second-order contributions from two- and three-body forces then provide the additional attraction required to reach the phenomenological depth. The imaginary part of the optical potential, which is positive (negative) for momenta below (above) the Fermi momentum, arises at second-order and is nearly inversion-symmetric about the Fermi surface when two-nucleon interactions alone are present. The imaginary part is strongly absorptive and requires the inclusion of an effective mass correction as well as self-consistent single-particle energies to attain qualitative agreement with phenomenology.

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