超核研究：无核壳模型中的轻中子富集氦锂同位素

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"这篇研究论文详细探讨了在无核壳模型中使用重要性截断方法对富含轻中子的超核进行的系统性研究。研究范围涵盖了从氦同位素HeΛ5到HeΛ11，以及锂同位素LiΛ7到LiΛ12的整个链。该工作基于手性有效场理论的两重子和三重子相互作用，通过相似性重整化组变换来优化模型空间的收敛性。" 在核物理学领域，超核是包含奇异粒子（如超子）的原子核，它们对于理解核力和宇宙中元素的形成过程具有重要意义。本研究的标题指出，关注的是那些含有轻中子的超核，特别是氦和锂的同位素，这些同位素由于其独特的核结构和性质，对于研究核的稳定性和反应机制提供了宝贵的信息。 "重要性截断的无核壳模型"是一种计算核物理的方法，它允许研究人员在有限的计算资源下，精确地处理复杂的核系统。在这个模型中，最显著的配置被优先考虑，从而减少了计算的复杂性，同时保持了结果的准确性。这种方法对于研究大型核系统，如本文涉及的富含轻中子的超核，是非常有效的。文章中提到了使用"手性有效场理论"，这是一种描述强相互作用的有效理论，它在低能量下能够准确预测核子和超子之间的相互作用。两重子和三重子相互作用是指由两个或三个核子（或超子）组成的复合粒子之间的相互作用，这是理解核结构和反应的关键。此外，"相似性重整化组变换"是一种技术，用于改进模型空间的收敛性。这种变换可以逐步改变核力的表示，使得在不同尺度上的计算结果趋于一致，从而提高理论预测的精度。关键词包括"Hypernuclei"（超核）、"Ab-initio methods"（从头开始的方法）、"Neutron-rich nuclei"（富含中子的核）、"Neutron separation energies"（中子分离能）和"Neutron dripline"（中子滴线）。这些关键词揭示了研究的核心内容：通过从头开始的计算方法研究富含中子的超核，特别是关注它们的稳定性和中子分离能，后者是衡量核稳定性的一个关键指标，而中子滴线则定义了中子最外层的边界。这项研究通过无核壳模型和重要性截断技术，深入分析了富含轻中子的超核的基态和激发能，这对于理解核结构、核力和宇宙中元素的生成具有深远意义。同时，通过手性有效场理论和相似性重整化组变换，提高了计算的精确度，为未来相关领域的研究提供了坚实的基础。

Physics Letters B 779 (2018) 336–341

Contents lists available at ScienceDirect

Physics Letters B

www.elsevier.com/locate/physletb

Light neutron-rich hypernuclei from the importance-truncated no-core

shell model

Roland Wirth

∗

, Robert Roth

Institut für Kernphysik – Theoriezentrum, Technische Universität Darmstadt, Schlossgartenstr. 2, 64289 Darmstadt, Germany

a r t i c l e i n f o a b s t r a c t

Article history:

Received

13 October 2017

Received

in revised form 29 January 2018

Accepted

12 February 2018

Available

online 13 February 2018

Editor:

J.-P. Blaizot

Keywords:

Hypernuclei

Ab-initio

methods

Neutron-rich

nuclei

Neutron

separation energies

Neutron

drip line

We explore the systematics of ground-state and excitation energies in singly-strange hypernuclei

throughout the helium and lithium isotopic chains — from



He to



He and from



Li to



Li — in the

ab initio no-core shell model with importance truncation. All calculations are based on two- and three-

baryon

interaction from chiral effective ﬁeld theory and we employ a similarity renormalization group

transformation consistently up to the three-baryon level to improve the model-space convergence. While

the absolute energies of hypernuclear states show a systematic variation with the regulator cutoff of

the hyperon–nucleon interaction, the resulting neutron separation energies are very stable and in good

agreement with available data for both nucleonic parents and their daughter hypernuclei. We provide

predictions for the neutron separation energies and the spectra of neutron-rich hypernuclei that have not

yet been observed experimentally. Furthermore, we ﬁnd that the neutron drip lines in the helium and

lithium isotopic chains are not changed by the addition of a hyperon.

(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP

1. Introduction

The exploration of the extremes of nuclear existence is one

of the main drivers in low-energy nuclear physics today. Current

and future experimental facilities, like FAIR, FRIB, JLab, J-Parc, or

RIBF, strive for more and more neutron-rich nuclei, approaching

the neutron drip line. The structure of nuclei with large neutron

excess provides valuable information about less-constrained parts

of the nuclear interaction and is a challenge for nuclear theory.

Light neutron-rich nuclei are an ideal testing ground for exploring

nuclear interactions at large neutron-to-proton ratios. At the same

time, heavier neutron-rich nuclei play a crucial role in nucleosyn-

thesis

processes in astrophysical environments, i.e., the r process

responsible for the production of the majority of heavy elements

in the universe [1]. Likewise, the strong interaction at the neutron-

rich

extremes governs the structure and stability of neutron stars

[2,3].

Strangeness

in nuclei has also been a focus of experimental and

theoretical activity [4]. A recent highlight are the mirror hypernu-

clei



H and



He, which exhibit a marked charge-symmetry break-

ing

effect [5–8]. Beyond these very light systems, which can be

Corresponding author.

E-mail

addresses: roland .wirth @physik.tu -darmstadt .de (R. Wirth),

robert .roth @physik.tu -darmstadt .de (R. Roth).

described theoretically with established ab initio few-body meth-

ods

[9,10], a multitude of phenomenological models like mean-

ﬁeld

[11,12], Skyrme [13–15], cluster [16,17]or microscopic shell

models [18,19]have been used to describe heavier hypernuclei.

Also, quantum Monte Carlo methods have been developed [20,21],

which can calculate ground-state energies throughout a large part

of the hypernuclear chart but are limited to simpliﬁed interactions.

Recently, we presented a powerful ab initio method suitable for

p-shell hypernuclei: the importance-truncated no-core shell model

(IT-NCSM) for hypernuclei [22]. With the IT-NCSM we can com-

pute

not only ground, but also excited states including all relevant

electromagnetic observables [23,24]. In order to accelerate the con-

vergence

of the IT-NCSM we employ similarity renormalization

group (SRG) transformations and we recently extended the SRG

to hyperon–nucleon (YN) and induced hyperon–nucleon–nucleon

(YNN) interactions [25].

this work, we connect the worlds of neutron-rich nuclei and

strangeness. We explore light neutron-rich hypernuclei and study

the impact of the additional hyperon on their structure. In partic-

ular,

we consider the helium and lithium isotopic chains and their

hypernuclear analogs. Some of these hypernuclei have been stud-

ied

in experiment [26–29], others can in principle be produced

but have not been observed [30]. Some are not accessible in ex-

periments

that produce hypernuclei off stable targets. However,

the possibility of using heavy ion collisions to produce hypernuclei

https://doi.org/10.1016/j.physletb.2018.02.021

0370-2693/

SCOAP

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