Transverse single spin asymmetries of forward neutrons in p+p, p+Al, and p+Au collisions at √sNN = 200 GeV as a function of transverse and longitudinal momenta
Transverse single spin asymmetries of forward neutrons in p+p, p+Al, and p+Au collisions at √sNN = 200 GeV as a function of transverse and longitudinal momenta
复制标题
√sNN = 200 GeV 时 p+p、p+Al 和 p+Au 碰撞中正向中子的横向单自旋不对称性与横向和纵向动量的函数关系
DOI：
10.1103/physrevd.105.032004
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发表时间：
2022
影响因子：
5
通讯作者：
PHENIX Collaboration
中科院分区：
文献类型：
--
作者：
Acharya U.A.;Esumi S. 他;PHENIX Collaboration
2015年，在相对论重离子对撞机上的PHENIX合作项目记录了，，和在质量中心能量为的质子束横向极化的碰撞数据。在非常向前rapidities相对于极化质子束，中子被检测到包括或（反）与探测器活动有关的硬碰撞。由此产生的单自旋不对称性，这是以前报道的，现在已经提取作为中子的横向动量的函数，以及其纵向动量分数。明确的运动学依赖性，结合相关信息，可以更仔细地研究不同机制的相互作用，建议描述这些不对称性，如强子相互作用或电磁相互作用的超周边碰撞，UPC。与硬碰撞相关的事件确实显示出大部分为负的不对称性，其幅度作为横向动量的函数而增加，只有很小的依赖性。相反，不太可能从硬碰撞中出现的事件显示出核碰撞的正不对称性，其运动学依赖性类似于基于UPC的模型。由于UPC相互作用强烈地依赖于核的电荷，这些影响对于碰撞非常小，对于碰撞中等，对于碰撞大。
In 2015 the PHENIX collaboration at the Relativistic Heavy Ion Collider recorded,, andcollision data at center of mass energies ofwith the proton beam(s) transversely polarized. At very forward rapiditiesrelative to the polarized proton beam, neutrons were detected either inclusively or in (anti)correlation with detector activity related to hard collisions. The resulting single spin asymmetries, that were previously reported, have now been extracted as a function of the transverse momentum of the neutron as well as its longitudinal momentum fraction. The explicit kinematic dependence, combined with the correlation information allows for a closer look at the interplay of different mechanisms suggested to describe these asymmetries, such as hadronic interactions or electromagnetic interactions in ultraperipheral collisions, UPC. Events that are correlated with a hard collision indeed display a mostly negative asymmetry that increases in magnitude as a function of transverse momentum with only little dependence on. In contrast, events that are not likely to have emerged from a hard collision display positive asymmetries for the nuclear collisions with a kinematic dependence that resembles that of a UPC based model. Because the UPC interaction depends strongly on the charge of the nucleus, those effects are very small forcollisions, moderate forcollisions, and large forcollisions.