Sun Kai-Jia, Liu Dai-Neng, Zheng Yun-Peng, Chen Jin-Hui, Ko Che Ming, Ma Yu-Gang
Fudan University, Institute of Modern Physics, Key Laboratory of Nuclear Physics and Ion-beam Application (MOE), Shanghai 200433, China.
Fudan University, Shanghai Research Center for Theoretical Nuclear Physics, NSFC and , Shanghai 200438, China.
Phys Rev Lett. 2025 Jan 17;134(2):022301. doi: 10.1103/PhysRevLett.134.022301.
Understanding the properties of hypernuclei is crucial for constraining the nature of hyperon-nucleon (Y-N) interactions, which plays a key role in determining the inner structure of compact stars. The lightest hypernuclei and antihypernuclei are the hypertriton ({Λ}^{3}H), which consists of a pair of nucleons and a Λ hyperon, and its antinucleus ({Λ[over ¯]}^{3}H[over ¯]). Significant knowledge has recently been acquired regarding the mass, lifetime, and binding energy of _{Λ}^{3}H. However, its exact spin, whether 1/2 or 3/2, remains undetermined in both experimental and theoretical studies. Here, we present a novel method of using the hypertriton global polarization in heavy-ion collisions to decipher not only its total spin but also its internal spin structure. This method is based on the finding that its three different spin structures exhibit distinct beam energy dependence of its global polarization when it is produced in these collisions from the coalescence of proton, neutron and Λ. Future observations of the hypertriton and antihypertriton global polarizations thus provide the opportunity to unveil the spin structures of hypertriton and antihypertriton and their production mechanisms in heavy-ion collisions.
了解超核的性质对于限制超子 - 核子（Y - N）相互作用的本质至关重要，而这种相互作用在确定致密星的内部结构中起着关键作用。最轻的超核和反超核是超氚核（({Λ}^{3}H)），它由一对核子和一个Λ超子组成，以及它的反核（({Λ[\overline{]}}^{3}H[\overline{]})）。最近已经获得了关于(_{Λ}^{3}H)的质量、寿命和结合能的重要知识。然而，在实验和理论研究中，其确切自旋是(1/2)还是(3/2)仍未确定。在此，我们提出一种在重离子碰撞中利用超氚核全局极化来不仅解读其总自旋而且解读其内部自旋结构的新方法。该方法基于这样一个发现，即当它在这些碰撞中由质子、中子和Λ聚结产生时，其三种不同的自旋结构对其全局极化表现出不同的束流能量依赖性。因此，未来对超氚核和反超氚核全局极化的观测为揭示超氚核和反超氚核的自旋结构及其在重离子碰撞中的产生机制提供了机会。
