原子核巨单极共振的统一描述与核物质不可压缩系数

Unified Description of Nuclear Giant Monopole Resonances and Nuclear Matter Incompressibility

原子核同位旋标量巨单极共振(ISGMR)的研究是约束核物质不可压缩系数K_(∞)的重要途径,对理解核天体物理现象提供了重要的信息。目前ISGMR研究中存在的一个重要问题是Sn和Pb中ISGMR不能够同时描述,即“为什么Sn同位素给出的状态方程这么软”,它阻碍了核物质不可压缩系数K_(∞)的精确约束。本文介绍原子核巨共振研究中常用的准粒子无规相位近似(QRPA)理论,和基于QRPA理论的自洽准粒子振动耦合(QPVC)理论,综述了基于QRPA理论和QRPA+QPVC理论对这一问题的研究现状,重点综述了QPVC效应对实现ISGMR统一描述的重要作用:通过考虑QPVC效应,能够实现对Sn和Pb同位素中ISGMR的统一描述,解决了“为什么Sn同位素给出的状态方程这么软”的问题,约束了核物质不可压缩系数K_(∞)。基于自洽的QPVC理论,还进一步研究了丰中子Sn同位素^(134,140)Sn的电单极激发强度分布。

The study of nuclear isoscalar giant monopole resonance(ISGMR)is an important way to constrain nuclear incompressibility coefficient,K_(∞)which provides important information for the understanding of nuclear astrophysics phenomena.At present,there is a serious discrepancy in the unified descriptions of the ISGMR in Pb and Sn isotopes,i.e.,the so called"why is the equation of state for tin so soft?",which prevents us from the accurate determination of K_(∞).In this paper,we introduce the quasiparticle random phase approximation(QRPA)theory,which is commonly used in the study of nuclear giant resonances,and also the self-consistent quasiparticle-vibration coupling(QPVC)theory based on the QRPA.The researches for the current issue within QRPA and QRPA+QPVC theories are reviewed,especially for the important role of the QPVC effects in achieving a unified description of ISGMR:a unified descriptions of ISGMR in Sn and Pb can be achieved with the QPVC effects,the problem"why is the equation of state for tin so soft?"can be solved,and the incompressibility coefficient K_(∞) is constrained.Besides,based on the self-consistent QPVC theory,we further studied the electric monopole excitation strength disctributions in the neutron-rich Sn isotopes ^(134,140)Sn.