近日，美国亚利桑那大学的U. van Kolck及其研究小组与巴西圣保罗大学的R. Higa等人合作并取得一项新进展。经过不懈努力，他们对接近二体幺正的四玻色子第一激发态进行研究。相关研究成果已于2024年4月1日在国际知名学术期刊《物理评论A》上发表。

该研究团队深入探讨了激发态与基态性质之间的内在联系，包括结合能和半径等要素，这些研究均在一个有效的场理论框架内展开，特别关注了短程力的影响，直至次领头阶。为了获取这些关联中的关键参数，研究人员借鉴了现有基于短时势的精确计算所产生的相似关联数据。此外，他们还巧妙地利用“晕”态的有效场论，成功推导出了从接近分裂阈值的状态到玻色子和三玻色子束缚态的激发态性质之间的关联性。

据悉，在接近二体幺正状态的情况下，三玻色子系统呈现出近似的离散尺度不变性，这一特性以束缚态的几何塔形式体现，即所谓的Efimov效应。而在没有强四体力作用的情况下，四玻色子系统则展现出与每个Efimov态相关联的两个独特状态。其中一个状态非常不稳定，而另一个状态则相对更深。

附：英文原文

Title: Four-boson first excited state near two-body unitarity

Author: Feng Wu, T. Frederico, R. Higa, U. van Kolck

Issue&Volume: 2024/04/01

Abstract: Near two-body unitarity, the three-boson system is characterized by an approximate discrete scale invariance manifest in a geometric tower of bound states (the Efimov effect). In the absence of a strong four-body force, the four-boson system has two states associated with each Efimov state, one very nearly unstable, the other several times deeper. We study correlations between the excited- and ground-state properties, such as binding energies and radii, up to next-to-leading order in an effective field theory for short-range forces. We obtain the parameters in these correlations from similar correlations arising from existing precise calculations based on short-range potentials. We also derive correlations among excited-state properties that emerge from the proximity of the state to the break-up threshold into a boson and a three-boson bound state, using an effective field theory for “halo” states.

DOI: 10.1103/PhysRevA.109.043301

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.043301