Global polarization of Λ and Λ ¯ hyperons in Au + Au collisions at s N N = 19.6 and 27 GeV

Journal Article · Thu Jul 27 00:00:00 EDT 2023 · Physical Review. C

DOI:https://doi.org/10.1103/physrevc.108.014910· OSTI ID:2222644

Abdulhamid, M. I.; Aboona, B. E.; Adam, J.; Adamczyk, L.; Adams, J. R.; Aggarwal, I.; Aggarwal, M. M.; Ahammed, Z.; Alpatov, E.; Anderson, D. M.; Aschenauer, E. C.; Aslam, S.; Atchison, J.; Bairathi, V.; Baker, W.; Ball Cap, J. G.; Barish, K.; Bellwied, R.; Bhagat, P.; Bhasin, A. ; Bhatta, S.; Bielcik, J.; Bielcikova, J.; Brandenburg, J. D.; Cai, X. Z.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Ceska, J.; Chakaberia, I.; Chaloupka, P.; Chan, B. K.; Chang, Z.; Chatterjee, A.; Chen, D.; Chen, J.; Chen, J. H.; Chen, Z.; Cheng, J.; Cheng, Y.; Choudhury, S.; Christie, W.; Chu, X.; Crawford, H. J.; Csanád, M.; Dale-Gau, G.; Das, A.; Daugherity, M.; Deppner, I. M.; Dhamija, A.; Di Carlo, L.; Didenko, L.; Dixit, P.; Dong, X.; Drachenberg, J. L.; Duckworth, E.; Dunlop, J. C.; Engelage, J.; Eppley, G.; Esumi, S.; Evdokimov, O.; Ewigleben, A.; Eyser, O.; Fatemi, R.; Fazio, S.; Feng, C. J.; Feng, Y.; Finch, E.; Fisyak, Y.; Flor, F. A.; Fu, C.; Gagliardi, C. A.; Galatyuk, T.; Geurts, F.; Ghimire, N.; Gibson, A.; Gopal, K.; Gou, X.; Grosnick, D.; Gupta, A.; Guryn, W.; Hamed, A.; Han, Y.; Harabasz, S.; Harasty, M. D.; Harris, J. W.; Harrison-Smith, H.; He, W.; He, X. H.; He, Y.; Herrmann, N.; Holub, L.; Hu, C.; Hu, Q.; Hu, Y.; Huang, H.; Huang, H. Z.; Huang, S. L.; Huang, T.; Huang, X.; Huang, Y.; Huang, Y.; Humanic, T. J.; Isenhower, D.; Isshiki, M.; Jacobs, W. W.; Jalotra, A.; Jena, C.; Jentsch, A.; Ji, Y.; Jia, J.; Jin, C.; Ju, X.; Judd, E. G.; Kabana, S.; Kabir, M. L.; Kagamaster, S.; Kalinkin, D.; Kang, K.; Kapukchyan, D.; Keane, D.; Kelsey, M.; Khyzhniak, Y. V.; Kikoła, D. P.; Kimelman, B.; Kincses, D.; Kisel, I.; Kiselev, A.; Knospe, A. G.; Ko, H. S.; Kosarzewski, L. K.; Kramarik, L.; Kumar, L.; Kumar, S.; Kunnawalkam Elayavalli, R.; Lacey, R.; Landgraf, J. M.; Lauret, J.; Lebedev, A.; Lee, J. H.; Leung, Y. H.; Lewis, N.; Li, C.; Li, W.; Li, X.; Li, Y.; Li, Y.; Li, Z.; Liang, X.; Liang, Y.; Licenik, R.; Lin, T.; Lisa, M. A.; Liu, C.; Liu, F.; Liu, G.; Liu, H.; Liu, H.; Liu, L.; Liu, T.; Liu, X.; Liu, Y.; Liu, Z.; Ljubicic, T.; Llope, W. J.; Lomicky, O.; Longacre, R. S.; Loyd, E. M.; Lu, T.; Lukow, N. S.; Luo, X. F.; Ma, L.; Ma, R.; Ma, Y. G.; Magdy, N.; Mallick, D.; Margetis, S.; Markert, C.; Matis, H. S.; Mazer, J. A.; McNamara, G.; Mi, K.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Mooney, I.; Mukherjee, A.; Nagy, M. I.; Nain, A. S.; Nam, J. D.; Nasim, M.; Neff, D.; Nelson, J. M.; Nemes, D. B.; Nie, M.; Nigmatkulov, G.; Niida, T.; Nishitani, R.; Nonaka, T.; Odyniec, G.; Ogawa, A.; Oh, S.; Okubo, K.; Page, B. S.; Pak, R.; Pan, J.; Pandav, A.; Pandey, A. K.; Pani, T.; Paul, A.; Pawlik, B.; Pawlowska, D.; Perkins, C.; Pluta, J.; Pokhrel, B. R.; Posik, M.; Protzman, T.; Prozorova, V.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qin, Z.; Qiu, H.; Quintero, A.; Racz, C.; Radhakrishnan, S. K.; Raha, N.; Ray, R. L.; Reed, R.; Ritter, H. G.; Robertson, C. W.; Robotkova, M.; Rosales Aguilar, M. A.; Roy, D.; Roy Chowdhury, P.; Ruan, L.; Sahoo, A. K.; Sahoo, N. R.; Sako, H.; Salur, S.; Sato, S.; Schmidke, W. B.; Schmitz, N.; Seck, F-J; Seger, J.; Seto, R.; Seyboth, P.; Shah, N.; Shanmuganathan, P. V.; Shao, T.; Sharma, M.; Sharma, N.; Sharma, R.; Sharma, S. R.; Sheikh, A. I.; Shen, D. Y.; Shen, K.; Shi, S. S.; Shi, Y.; Shou, Q. Y.; Si, F.; Singh, J.; Singha, S.; Sinha, P.; Skoby, M. J.; Smirnov, N.; Söhngen, Y.; Song, Y.; Srivastava, B.; Stanislaus, T. S.; Stefaniak, M.; Stewart, D. J.; Stringfellow, B.; Su, Y.; Suaide, A. P.; Sumbera, M.; Sun, C.; Sun, X.; Sun, Y.; Sun, Y.; Surrow, B.; Sweger, Z. W.; Szymanski, P.; Tamis, A.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tomkiel, C. A.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Truhlar, T.; Trzeciak, B. A.; Tsai, O. D.; Tsang, C. Y.; Tu, Z.; Tyler, J.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; Vanek, J.; Vassiliev, I.; Verkest, V.; Videbæk, F.; Voloshin, S. A.; Wang, F.; Wang, G.; Wang, J. S.; Wang, X.; Wang, Y.; Wang, Y.; Wang, Y.; Wang, Z.; Webb, J. C.; Weidenkaff, P. C.; Westfall, G. D.; Wielanek, D.; Wieman, H.; Wilks, G.; Wissink, S. W.; Witt, R.; Wu, J.; Wu, J.; Wu, X.; Wu, Y.; Xi, B.; Xiao, Z. G.; Xie, G.; Xie, W.; Xu, H.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Y.; Xu, Z.; Xu, Z.; Yan, G.; Yan, Z.; Yang, C.; Yang, Q.; Yang, S.; Yang, Y.; Ye, Z.; Ye, Z.; Yi, L.; Yip, K.; Yu, Y.; Zbroszczyk, H.; Zha, W.; Zhang, C.; Zhang, D.; Zhang, J.; Zhang, S.; Zhang, W.; Zhang, X.; Zhang, Y.; Zhang, Y.; Zhang, Y.; Zhang, Z. J.; Zhang, Z.; Zhang, Z.; Zhao, F.; Zhao, J.; Zhao, M.; Zhou, C.; Zhou, J.; Zhou, S.; Zhou, Y.; Zhu, X.; Zurek, M.; Zyzak, M.

In relativistic heavy-ion collisions, a global spin polarization, P_H, of Λ and Λ¯¯ hyperons along the direction of the system angular momentum was discovered and measured across a broad range of collision energies and demonstrated a trend of increasing P_H with decreasing $$\sqrt{s{NN}}$$. A splitting between Λ and Λ¯¯ polarization may be possible due to their different magnetic moments in a late-stage magnetic field sustained by the quark-gluon plasma which is formed in the collision. The results presented in this study find no significant splitting at the collision energies of $$\sqrt{s{NN}}$$ = 19.6 and 27 GeV in the BNL Relativistic Heavy Ion Collisions Beam Energy Scan Phase II using the STAR detector, with an upper limit of P_Λ¯¯ – P_Λ < 0.24 % and P_Λ¯¯ – P_Λ < 0.35 %, respectively, at a 95% confidence level. We derive an upper limit on the naive extraction of the late-stage magnetic field of B < 9.4 × 10¹² T and B < 1.4 × 10¹³ T at $$\sqrt{s{NN}}$$ = 19.6 and 27 GeV, respectively, although more thorough derivations are needed. Differential measurements of P_H were performed with respect to collision centrality, transverse momentum, and rapidity. With our current acceptance of |y| < 1 and uncertainties, we observe no dependence on transverse momentum and rapidity in this analysis. These results challenge multiple existing model calculations following a variety of different assumptions which have each predicted a strong dependence on rapidity in this collision-energy range.

• Research Organization: Texas A & M Univ., College Station, TX (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• Contributing Organization: STAR Collaboration
• Grant/Contract Number: SC0017982
• OSTI ID: 2222644
• Journal Information: Physical Review. C, Vol. 108, Issue 1; ISSN 2469-9985
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
Particle correlations &amp; fluctuations
Polarization phenomena
Relativistic heavy-ion collisions