This work presents further analysis of the three- and four-neutron systems in the low energy regime using adiabatic hyperspherical methods. In our previous article [M. D. Higgins et al., Phys. Rev. Lett. 125, 052501 (2020)], the low-energy behavior of these neutron systems was treated in the adiabatic approximation, neglecting the off-diagonal nonadiabatic couplings. A thorough analysis of the density of states through a multichannel treatment of the three-and four-neutron scattering near the scattering continuum threshold is performed, showing no evidence of a $4n$ resonance at low energy. A detailed analysis of the long-range behavior of the lowest few adiabatic hyperspherical potentials shows there is an attractive ${\rho }^{-3}$ universal behavior which dominates in the low-energy regime of the multichannel scattering. This long-range behavior leads to a divergent behavior of the density of state for $E\to 0$ that could account for the low-energy signal observed in the 2016 experiment by Kisamori et al. [Phys. Rev. Lett. 116, 052501 (2016)].

中文翻译：

---

低能量三中子和四中子系统的综合研究

这项工作提出了使用绝热超球面方法对低能态的三中子和四中子系统的进一步分析。在我们以前的文章中[M. D.希金斯等。，物理 牧师 125，052501（2020）]，这些中子系统的低能量的行为是在绝热近似处理，而忽略了非对角线非绝热耦合。通过对散射连续谱阈值附近的三和四中子散射进行多通道处理，对状态密度进行了彻底的分析，没有证据表明存在$4ñ$低能量共振。对最低绝热超球形势的远距离行为进行的详细分析表明，存在一种有吸引力的方法${\rho }^{-3}$在多通道散射的低能状态下占主导地位的普遍行为。这种远距离行为导致状态密度的发散行为。$E\to 0$这可以解释Kisamori等人在2016年实验中观察到的低能信号。[物理 牧师 116，052501（2016）]。