학술논문
Measurement of transverse single-spin asymmetries of $\pi^0$ and electromagnetic jets at forward rapidity in 200 and 500 GeV transversely polarized proton-proton collisions
Document Type
Working Paper
Author
STAR Collaboration; Adam, J.; Adamczyk, L.; Adams, J. R.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Anderson, D. M.; Aparin, A.; Aschenauer, E. C.; Ashraf, M. U.; Atetalla, F. G.; Attri, A.; Averichev, G. S.; Bairathi, V.; Barish, K.; Behera, A.; Bellwied, R.; Bhasin, A.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Brandenburg, J. D.; Brandin, A. V.; Butterworth, J.; Caines, H.; Sánchez, M. Calderón de la Barca; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chan, B. K.; Chang, F-H.; Chang, Z.; Chankova-Bunzarova, N.; Chatterjee, A.; Chen, D.; Chen, J.; Chen, J. H.; Chen, X.; Chen, Z.; Cheng, J.; Cherney, M.; Chevalier, M.; Choudhury, S.; Christie, W.; Chu, X.; Crawford, H. J.; Csanád, M.; Daugherity, M.; Dedovich, T. G.; Deppner, I. M.; Derevschikov, A. A.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Dunlop, J. C.; Edmonds, T.; Elsey, N.; Engelage, J.; Eppley, G.; Esumi, S.; Evdokimov, O.; Ewigleben, A.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, C. J.; Feng, Y.; Filip, P.; Finch, E.; Fisyak, Y.; Francisco, A.; Fulek, L.; Gagliardi, C. A.; Galatyuk, T.; Geurts, F.; Ghimire, N.; Gibson, A.; Gopal, K.; Gou, X.; Grosnick, D.; Guryn, W.; Hamad, A. I.; Hamed, A.; Harabasz, S.; Harris, J. W.; He, S.; He, W.; He, X. H.; He, Y.; Heppelmann, S.; Herrmann, N.; Hoffman, E.; Holub, L.; Hong, Y.; Horvat, S.; Hu, Y.; Huang, H. Z.; Huang, S. L.; Huang, T.; Huang, X.; Humanic, T. J.; Huo, P.; Igo, G.; Isenhower, D.; Jacobs, W. W.; Jena, C.; Jentsch, A.; Ji, Y.; Jia, J.; Jiang, K.; Jowzaee, S.; Ju, X.; Judd, E. G.; Kabana, S.; Kabir, M. L.; Kagamaster, S.; Kalinkin, D.; Kang, K.; Kapukchyan, D.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kelsey, M.; Khyzhniak, Y. V.; Kikoła, D. P.; Kim, C.; Kimelman, B.; Kincses, D.; Kinghorn, T. A.; Kisel, I.; Kiselev, A.; Kocan, M.; Kochenda, L.; Kosarzewski, L. K.; Kramarik, L.; Kravtsov, P.; Krueger, K.; Mudiyanselage, N. Kulathunga; Kumar, L.; Kumar, S.; Elayavalli, R. Kunnawalkam; Kwasizur, J. H.; Lacey, R.; Lan, S.; Landgraf, J. M.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Leung, Y. H.; Li, C.; Li, W.; Li, X.; Li, Y.; Liang, Y.; Licenik, R.; Lin, T.; Lin, Y.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, P.; Liu, T.; Liu, X.; Liu, Y.; Liu, Z.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Lukow, N. S.; Luo, S.; Luo, X.; Ma, G. L.; Ma, L.; Ma, R.; Ma, Y. G.; Magdy, N.; Majka, R.; Mallick, D.; Margetis, S.; Markert, C.; Matis, H. S.; Mazer, J. A.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Mooney, I.; Moravcova, Z.; Morozov, D. A.; Nagy, M.; Nam, J. D.; Nasim, Md.; Nayak, K.; Neff, D.; Nelson, J. M.; Nemes, D. B.; Nie, M.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Nonaka, T.; Nunes, A. S.; Odyniec, G.; Ogawa, A.; Oh, S.; Okorokov, V. A.; Page, B. S.; Pak, R.; Pandav, A.; Panebratsev, Y.; Pawlik, B.; Pawlowska, D.; Pei, H.; Perkins, C.; Pinsky, L.; Pintér, R. L.; Pluta, J.; Pokhrel, B. R.; Porter, J.; Posik, M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qiu, H.; Quintero, A.; Radhakrishnan, S. K.; Ramachandran, S.; Ray, R. L.; Reed, R.; Ritter, H. G.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Sahoo, N. R.; Sako, H.; Salur, S.; Sandweiss, J.; Sato, S.; Schmidke, W. B.; Schmitz, N.; Schweid, B. R.; Seck, F.; Seger, J.; Sergeeva, M.; Seto, R.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sheikh, A. I.; Shen, W. Q.; Shi, S. S.; Shi, Y.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singh, J.; Singha, S.; Smirnov, N.; Solyst, W.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stefaniak, M.; Stewart, D. J.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Sumbera, M.; Summa, B.; Sun, X. M.; Sun, X.; Sun, Y.; Surrow, B.; Svirida, D. N.; Szymanski, P.; Tang, A. H.; Tang, Z.; Taranenko, A.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Tomkiel, C. A.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Tu, Z.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; Vanek, J.; Vasiliev, A. N.; Vassiliev, I.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Wang, F.; Wang, G.; Wang, J. S.; Wang, P.; Wang, Y.; Wang, Z.; Webb, J. C.; Weidenkaff, P. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, G.; Xie, W.; Xu, H.; Xu, N.; Xu, Q. H.; Xu, Y. F.; Xu, Y.; Xu, Z.; Yang, C.; Yang, Q.; Yang, S.; Yang, Y.; Yang, Z.; Ye, Z.; Yi, L.; Yip, K.; Yu, Y.; Zbroszczyk, H.; Zha, W.; Zhang, C.; Zhang, D.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. J.; Zhang, Z.; Zhao, J.; Zhong, C.; Zhou, C.; Zhu, X.; Zhu, Z.; Zurek, M.; Zyzak, M.
Source
Phys. Rev. D 103, 092009 (2021)
Subject
Language
Abstract
The STAR Collaboration reports measurements of the transverse single-spin asymmetry (TSSA) of inclusive $\pi^0$ at center-of-mass energies ($\sqrt s$) of 200 GeV and 500 GeV in transversely polarized proton-proton collisions in the pseudo-rapidity region 2.7 to 4.0. The results at the two different energies show a continuous increase of the TSSA with Feynman-$x$, and, when compared to previous measurements, no dependence on $\sqrt s$ from 19.4 GeV to 500 GeV is found. To investigate the underlying physics leading to this large TSSA, different topologies have been studied. $\pi^0$ with no nearby particles tend to have a higher TSSA than inclusive $\pi^0$. The TSSA for inclusive electromagnetic jets, sensitive to the Sivers effect in the initial state, is substantially smaller, but shows the same behavior as the inclusive $\pi^0$ asymmetry as a function of Feynman-$x$. To investigate final-state effects, the Collins asymmetry of $\pi^0$ inside electromagnetic jets has been measured. The Collins asymmetry is analyzed for its dependence on the $\pi^0$ momentum transverse to the jet thrust axis and its dependence on the fraction of jet energy carried by the $\pi^0$. The asymmetry was found to be small in each case for both center-of-mass energies. All the measurements are compared to QCD-based theoretical calculations for transverse-momentum-dependent parton distribution functions and fragmentation functions. Some discrepancies are found, which indicates new mechanisms might be involved.
Comment: after replying to referee's comments. minor changes
Comment: after replying to referee's comments. minor changes