相对论重离子对撞中奇异强子产生机制的实验研究进展  

Progress in experimental studies of the mechanism of strange hadron production in relativistic heavy-ion collisions

作　　者：陈金辉 马余刚 朱相雷[2] Jinhui Chen;Yu-Gang Ma;Xianglei Zhu(Key Laboratory of Nuclear Physics and Ion-beam Application,Ministry of Education,Institute of Modern Physics,Fudan University,Shanghai 200433,China;Department of Engineering Physics,Tsinghua University,Beijing 100084,China)

机构地区：[1]复旦大学现代物理研究所,核物理与离子束应用教育部重点实验室,上海200433 [2]清华大学工程物理系,北京100084

出　　处：《科学通报》2021年第34期4358-4367,共10页Chinese Science Bulletin

基　　金：国家自然科学基金(12025501,11890714,11775288);中国科学院B类战略性先导科技专项(XDB34030200)资助。

摘　　要：相对论重离子对撞是实验室研究夸克物质的理想途径,其中奇异性增强是寻找和研究新物质形态夸克胶子等离子体(quark-gluon plasma, QGP)的重要探针之一.本文系统阐述了我们课题组在奇异强子产生实验研究方面的几个工作,包括:(1)奇异强子产生机制的实验测量.从奇异夸克动力学角度研究QGP性质,并研究其产额比与量子色动力学(quantum chromodynamics, QCD)物质相变的联系,发现在金核+金核对撞能量大于或小于√^(s)NN=19.6 GeV的实验区间,奇异强子产额随着横向动量变化出现显著差异.例如,在束流能量大于或等于19.6 GeV时,多奇异性强子产额比符合夸克并合模型描述;在束流能量小于19.6 GeV能区,该实验数据迅速偏离夸克并合模型计算结果,这可能是QCD相变的信号.(2)奇异性原子核-超氚核质量和结合能的精确测量.实验结果以高精度验证了电荷-宇称-时间(charge, parity, time, CPT)联合变换不变性在超氚核-反超氚核系统上成立,实现了CPT对称性在迄今为止最重反物质原子核上的检验,测量结果将为扩展标准模型参数提供实验限制.同时,发现超氚核结合能远大于0,更新了近50年前的测量结果,回应了长期困扰学界的超氚核结合能的"Dalitz之惑".新的测量结果也为理论计算超子-核子之间相互作用提供了更为精确的限制.(3)多奇异强子-核子相互作用的测量.实验结果提供了奇异数S=-3的Ω超子与奇异数S=0的质子作用强度的第一手数据,发现它们之间存在强吸引作用,有望形成奇异双重子态,检验了质子-Ω双重子态的理论假设.这些研究丰富了人们对强相互作用,尤其是QGP中奇异强子产额增强、物质-反物质基本对称性和多奇异性强子奇特态等的认识.Relativistic heavy-ion collision is an ideal way to study the quark matter in laboratory, among which strangeness enhancement is one of the significant probes to search and study the new state of matter, the quark gluon plasma(QGP).Several of our efforts on experimental studies of the strange hadron production are discussed systematically in this review.They include:(1) Measurement of strange hadron production at relativistic heavy-ion collider(RHIC), to study the nature of QGP from the probe of strange quark dynamics, and explore the relationship between strange hadron yield ratio and the quantum chromodynamics(QCD) phase transition, where our data seem to present a clear difference of strange hadron production as a function of their transverse momentum in Au+Au collisions above or lower than the center of mass energy √^(s)NN=19.6 GeV. For example, the multistrange hadron yield ratio is consistent with the quark coalescence model prediction when the collision energy is equal to or larger than 19.6 GeV, favoring the formation of QGP in such collisions;when the collision energy is lower than 19.6 GeV, the yield ratio rapidly deviates from quark coalescence model calculation result, suggesting the importance of hadronic degree of freedom in such collisions. Such a clear difference of strange hadron yield ratio vs. collision energies may be an experimental signal of the QCD phase transition, although statistical uncertainty is still large.(2) Accurate measurement of the mass and the binding energy of the strange nuclei, the hypertriton and the antihypertriton, where the high precision mass measurement data support the CPT(charge, parity, time) invariant in hypertriton and antihypertriton system. So far, this is the CPT invariant test in most heavy antimatter nuclei ever explored.The measurement will also provide experimental constraint on the standard model extension(SME) parameterization.Meanwhile, we obtain the binding energy of hypertriton far above zero. It updates the commonly used data of nearly50 years ago

关 键 词：相对论重离子对撞 夸克胶子等离子体 奇异性增强 奇异强子 超氚核 超子-核子相互作用 

分 类 号：O571.6[理学—粒子物理与原子核物理]