Transverse single-spin asymmetry for very forward neutral pion production in polarized $p+p$ collisions at $\sqrt{s} = 510$ GeV
| Autor: | Kim, M. H., Adriani, O., Berti, E., Bonechi, L., D'Alessandro, R., Goto, Y., Hong, B., Itow, Y., Kasahara, K., Menjo, H., Nakagawa, I., Park, J. S., Sako, T., Sakurai, N., Sato, K., Seidl, R., Tanida, K., Torii, S., Tricomi, A., Ueno, M., Makino, Y., Zhou, Q. D., Lee, J. H., Ljubicic, T., Ogawa, A. |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Phys. Rev. Lett. 124, 252501 (2020) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevLett.124.252501 |
| Popis: | Transverse single-spin asymmetries of very forward neutral pions generated in polarized $p + p$ collisions allow us to understand the production mechanism in terms of perturbative and non-perturbative strong interactions. During 2017 the RHICf Collaboration installed an electromagnetic calorimeter in the zero-degree region of the STAR detector at the Relativistic Heavy Ion Collider (RHIC) and measured neutral pions produced at pseudorapidity larger than 6 in polarized $p$+$p$ collisions at $\sqrt{s}$ = 510 GeV. The large non-zero asymmetries increasing both in longitudinal momentum fraction $x_{F}$ and transverse momentum $p_{T}$ have been observed at low transverse momentum $p_{T} < 1$ GeV/$c$ for the first time at this collision energy. The asymmetries show an approximate $x_{F}$ scaling in the $p_{T}$ region where non-perturbative processes are expected to dominate. A non-negligible contribution from soft processes may be necessary to explain the nonzero neutral pion asymmetries. Comment: This paper submitted to PRL is the final result of arXiv:1902.07852 |
| Databáze: | arXiv |
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