Large transverse asymmetry observed in neutral pion production in polarized proton-proton collisions - New research deepens mystery of particle generation in proton collision -


A group of researchers including scientists from the RIKEN Nishina Center for Accelerator-Based Science, University of Tokyo, Nagoya University, and the Japan Atomic Energy Agency (JAEA) used the spin-polarized Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in the United States to show that, in polarized proton-proton collisions, neutral pions emitted in the very forward area of collisions—where direct interactions involving quarks and gluons are not applicable—still have a large degree of left-right asymmetry. This finding suggests that the previous consensus regarding the generation of particles in such collisions needs to be reevaluated. Prof. Yoshitaka Itow and Dr. Hiroaki Menjo are actively involved in the project.

Large transverse (left-right) asymmetry observed for neutral pions produced in the very forward region of polarized proton-proton collisions.

Related links
Press release by RIKEN

Press release by KMI, Nagoya University

Behind the scenes (Japanese)

RHICf Experiment webpage

Paper Information
Transverse single-spin asymmetry for very forward neutral pion production in polarized p + p collisions at = 510 GeV

M. H. Kim et al. [RHICf Collaboration]

Physical Review Letters 124, 252501 (2020)
DOI: 10.1103/PhysRevLett.124.252501