Abstract
During 2015, the Relativistic Heavy Ion Collider (RHIC) provided collisions of transversely polarized protons with Au and Al nuclei for the first time, enabling the exploration of transverse-single-spin asymmetries with heavy nuclei. Large single-spin asymmetries in very forward neutron production have been previously observed in transversely polarized collisions at RHIC, and the existing theoretical framework that was successful in describing the single-spin asymmetry in collisions predicts only a moderate atomic-mass-number () dependence. In contrast, the asymmetries observed at RHIC in collisions showed a surprisingly strong dependence in inclusive forward neutron production. The observed asymmetry in collisions is much smaller, while the asymmetry in collisions is a factor of 3 larger in absolute value and of opposite sign. The interplay of different neutron production mechanisms is discussed as a possible explanation of the observed dependence.
- Received 3 April 2017
- Revised 26 September 2017
DOI:https://doi.org/10.1103/PhysRevLett.120.022001
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.
Published by the American Physical Society