摘要
宇宙正反物质的不对称性起源是当今科学的重要未解之谜.本文简要评述反物质研究历程和近期国际上的相关研究热点.重点阐述了近些年来,在相对论重离子碰撞实验中取得的反物质研究进展,包括发现首个反物质超核(反超氚)、反物质氦4、反超氢4、反质子相互作用的首次测量、正反超氚核的质量和结合能的精确测量等.在此基础上,我们讨论了(反)轻核产生的不同物理机制.同时,也介绍了反氢原子实验、太空探测反物质等方面取得的最新成果,并讨论这些进展对认识物质结构的启示.
Abstract
The asymmetric origin of matter and antimatter in the universe is an important unsolved mystery in science today.In this paper,we briefly review the history of antimatter research and the recent international hotspots of related research.This paper focuses on the advances in antimatter research made in recent years at the large-scale international RHIC-STAR experiment at the Relativistic Heavy Ion Collider,including the discovery of the first antimatter hypernucleus(anti-hypertriton),antimatter helium 4 and antihyperhydrogen 4,the first measurements of antiproton interactions,and the precise measurements of the mass and binding energy of the hypertriton and anti-hypertriton.The antimatter hypertriton nucleus,composed of an antiproton,an antineutron,and an anti-Λ hyperon,is the first anti-hypernucleu to be discovered,extending the three-dimensional nuclide map from the anti-strange quark degree of freedom.Antimatter Helium 4 is the heaviest stable antimatter nucleus yet discovered.Anti-hyperhydrogen 4,just discovered in 2024,is composed of an antiproton,two antineutrons,and an anti-Λ hyperon,and is the heaviest antimatter hypernucleus to date.Equivalence to the proton-proton interaction was established by measurements of the antiproton-antiproton interaction.At the same time,precise measurements of the mass of hypertriton and anti-hypertriton nuclei confirmed the equivalence of matter and antimatter.And these also fully demonstrate that the CPT symmetry is also valid for antimatter nuclei.Measurements of the binding energy of the hypertriton nucleus indicate that the interaction between Λ and the nucleus of the hypertriton(the deuterium nucleus)is strong,which differs from the earlier common belief that the hypertriton nucleus is a weakly bound system.Furthermore,we discuss different physical mechanisms for the production of(anti)light nuclei,mainly including thermal,coalescence and relativistic kinetic models.Finally,we also present recent results from antihydrogen atom experiments at CERN,antimatter space probes,etc.,and discuss the implications of these advances for understanding the structure of matter.Overall,the existing studies of antimatter nuclei and atoms have not yet provided clear evidence for the asymmetric origin of matter and antimatter in the universe,which can help further improve the accuracy of various measurements in antimatter research.Of course,other efforts in this direction in nuclear and particle physics are well expected.
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