The longitudinal spin transfer DLL to Λ and Λ¯ hyperons produced in high-energy polarized proton--proton collisions is expected to be sensitive to the helicity distribution functions of strange quarks and anti-quarks of the proton, and to longitudinally polarized fragmentation functions. We report an improved measurement of DLL from data obtained at a center-of-mass energy of s√ = 200 GeV with the STAR detector at RHIC. The data have an approximately twelve times larger figure-of-merit than prior results and cover |η|< 1.2 in pseudo-rapidity with transverse momenta pT up to 6 GeV/c. In the forward scattering hemisphere at largest pT, the longitudinal spin transfer is found to be DLL = -0.036 ± 0.048 (stat) ± 0.013(sys) for Λ hyperons and DLL = 0.032 ± 0.043\,(stat) ± 0.013\,(sys) for Λ¯ anti-hyperons. The dependences on η and pT are presented and compared with model evaluations.
Improved measurement of the longitudinal spin transfer to Λ and Λ hyperons in polarized proton-proton collisions at s =200 GeV / Adam, J.; Adamczyk, L.; Adams, J. R.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Anderson, D. M.; Aoyama, R.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Ashraf, M. U.; Atetalla, F.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Barish, K.; Bassill, A. J.; Behera, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Brandenburg, J. D.; Brandin, A. V.; Brown, D.; Bryslawskyj, J.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón De La Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Chakaberia, I.; Chaloupka, P.; Chan, B. K.; Chang, F. -H.; Chang, Z.; Chankova-Bunzarova, N.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Csanad, M.; Das, S.; Dedovich, T. G.; Deng, J.; Deppner, I. M.; Derevschikov, A. A.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Dunlop, J. C.; Efimov, L. G.; Elsey, N.; Engelage, J.; Eppley, G.; Esha, R.; Esumi, S.; Evdokimov, O.; Ewigleben, J.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Federicova, P.; Fedorisin, J.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Galatyuk, T.; Geurts, F.; Gibson, A.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Harlenderova, A.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Herrmann, N.; Hirsch, A.; Holub, L.; Hong, Y.; Horvat, S.; Huang, B.; Huang, H. Z.; Huang, S. L.; Huang, T.; Huang, X.; Humanic, T. J.; Huo, P.; Igo, G.; Jacobs, W. W.; Jentsch, A.; Jia, J.; Jiang, K.; Jowzaee, S.; Ju, X.; Judd, E. G.; Kabana, S.; Kagamaster, S.; Kalinkin, D.; Kang, K.; Kapukchyan, D.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kikoła, D. P.; Kim, C.; Kinghorn, T. A.; Kisel, I.; Kisiel, A.; Kochenda, L.; Kosarzewski, L. K.; Kraishan, A. F.; Kramarik, L.; Krauth, L.; Kravtsov, P.; Krueger, K.; Kulathunga, N.; Kumar, L.; Kunnawalkam Elayavalli, R.; Kvapil, J.; Kwasizur, J. H.; Lacey, R.; Landgraf, J. M.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, C.; Li, W.; Li, X.; Li, Y.; Liang, Y.; Lidrych, J.; Lin, T.; Lipiec, A.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, P.; Liu, P.; Liu, Y.; Liu, Z.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. 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.; Matonoha, O.; Mazer, J. A.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Mooney, I.; Morozov, D. A.; Nasim, Md.; Negrete, J. D.; Nelson, J. M.; Nemes, D. B.; Nie, M.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Nonaka, T.; Odyniec, G.; Ogawa, A.; Oh, K.; Oh, S.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pinter, R. L.; Pluta, J.; Porter, J.; Posik, M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Quintero, A.; Radhakrishnan, S. K.; Ramachandran, S.; Ray, R. L.; Reed, R.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Salur, S.; Sandweiss, J.; Schambach, J.; Schmah, A. M.; 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.; Shen, F.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Siejka, S.; Sikora, R.; Simko, M.; Singh, J.; Singha, S.; Smirnov, D.; Smirnov, N.; Solyst, W.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stewart, D. J.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Sugiura, T.; 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.; Todoroki, T.; Tokarev, M.; Tomkiel, C. A.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Tu, B.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; Vanek, J.; Vasiliev, A. N.; Vassiliev, I.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, F.; Wang, G.; Wang, P.; Wang, Y.; Wang, Y.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, G.; Xie, W.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y. F.; Xu, Z.; Yang, C.; Yang, Q.; Yang, S.; Yang, Y.; Ye, Z.; Ye, Z.; Yi, L.; Yip, K.; Yoo, I. -K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J.; Zhang, J.; Zhang, L.; Zhang, S.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z.; Zhao, J.; Zhong, C.; Zhou, C.; Zhu, X.; Zhu, Z.; Zyzak, M.. - In: PHYSICAL REVIEW D. - ISSN 2470-0010. - 98:11(2018), pp. 112009.1-112009.8. [10.1103/PhysRevD.98.112009]
Improved measurement of the longitudinal spin transfer to Λ and Λ hyperons in polarized proton-proton collisions at s =200 GeV
Contin, G.;
2018-01-01
Abstract
The longitudinal spin transfer DLL to Λ and Λ¯ hyperons produced in high-energy polarized proton--proton collisions is expected to be sensitive to the helicity distribution functions of strange quarks and anti-quarks of the proton, and to longitudinally polarized fragmentation functions. We report an improved measurement of DLL from data obtained at a center-of-mass energy of s√ = 200 GeV with the STAR detector at RHIC. The data have an approximately twelve times larger figure-of-merit than prior results and cover |η|< 1.2 in pseudo-rapidity with transverse momenta pT up to 6 GeV/c. In the forward scattering hemisphere at largest pT, the longitudinal spin transfer is found to be DLL = -0.036 ± 0.048 (stat) ± 0.013(sys) for Λ hyperons and DLL = 0.032 ± 0.043\,(stat) ± 0.013\,(sys) for Λ¯ anti-hyperons. The dependences on η and pT are presented and compared with model evaluations.| File | Dimensione | Formato | |
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PhysRevD.98.112009.pdf
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