/ nucl-ex arXiv:1701.06657


Global $\Lambda$ hyperon polarization in nuclear collisions: evidence for the most vortical fluid


Adamczyk, L. (AGH-UST, Cracow) ; Adkins, J.K. (U. Kentucky, Lexington) ; Agakishiev, G. (Dubna, JINR) ; Aggarwal, M.M. (Panjab U.) ; Ahammed, Z. (Calcutta, VECC) ; Ajitanand, N.N. (SUNY, Stony Brook) ; Alekseev, I. (Moscow Phys. Eng. Inst.) ; Anderson, D.M. (Texas A-M) ; Aoyama, R. (Tsukuba U.) ; Aparin, A. (Dubna, JINR) ; Arkhipkin, D. (Brookhaven) ; Aschenauer, E.C. (Brookhaven) ; Ashraf, M.U. (Tsinghua U., Beijing) ; Attri, A. (Panjab U.) ; Averichev, G.S. (Dubna, JINR) ; Bai, X. (Hua-Zhong Normal U.) ; Bairathi, V. (Bhubaneswar, NISER) ; Behera, A. (SUNY, Stony Brook) ; Bellwied, R. (Houston U.) ; Bhasin, A. (Jammu U.) ; Bhati, A.K. (Panjab U.) ; Bhattarai, P. (Texas U.) ; Bielcik, J. (Prague, Tech. U.) ; Bielcikova, J. (Charles U.) ; Bland, L.C. (Brookhaven) ; Bordyuzhin, I.G. (Moscow, ITEP) ; Bouchet, J. (Kent State U.) ; Brandenburg, J.D. (Rice U.) ; Brandin, A.V. (Moscow Phys. Eng. Inst.) ; Brown, D. (Lehigh U.) ; Bunzarov, I. (Dubna, JINR) ; Butterworth, J. (Rice U.) ; Caines, H. (Yale U.) ; Calderón de la Barca Sánchez, M. (UC, Davis) ; Campbell, J.M. (Ohio State U.) ; Cebra, D. (UC, Davis) ; Chakaberia, I. (Brookhaven) ; Chaloupka, P. (Prague, Tech. U.) ; Chang, Z. (Texas A-M) ; Chankova-Bunzarova, N. (Dubna, JINR) ; Chatterjee, A. (Calcutta, VECC) ; Chattopadhyay, S. (Calcutta, VECC) ; Chen, X. (Hefei, CUST) ; Chen, J.H. (SINAP, Shanghai) ; Chen, X. (Lanzhou, Inst. Modern Phys.) ; Cheng, J. (Tsinghua U., Beijing) ; Cherney, M. (Creighton U.) ; Christie, W. (Brookhaven) ; Contin, G. (LBL, Berkeley) ; Crawford, H.J. (UC, Berkeley) ; Das, S. (Hua-Zhong Normal U.) ; De Silva, L.C. (Creighton U.) ; Debbe, R.R. (Brookhaven) ; Dedovich, T.G. (Dubna, JINR) ; Deng, J. (Shandong U.) ; Derevschikov, A.A. (Serpukhov, IHEP) ; Didenko, L. (Brookhaven) ; Dilks, C. (Penn State U.) ; Dong, X. (LBL, Berkeley) ; Drachenberg, J.L. (Lamar U.) ; Draper, J.E. (UC, Davis) ; Dunkelberger, L.E. (UCLA) ; Dunlop, J.C. (Brookhaven) ; Efimov, L.G. (Dubna, JINR) ; Elsey, N. (Wayne State U.) ; Engelage, J. (UC, Berkeley) ; Eppley, G. (Rice U.) ; Esha, R. (UCLA) ; Esumi, S. (Tsukuba U.) ; Evdokimov, O. (Illinois U., Chicago) ; Ewigleben, J. (Lehigh U.) ; Eyser, O. (Brookhaven) ; Fatemi, R. (U. Kentucky, Lexington) ; Fazio, S. (Brookhaven) ; Federic, P. (Charles U.) ; Federicova, P. (Prague, Tech. U.) ; Fedorisin, J. (Dubna, JINR) ; Feng, Z. (Hua-Zhong Normal U.) ; Filip, P. (Dubna, JINR) ; Finch, E. (Southern Connecticut State U., New Haven) ; Fisyak, Y. (Brookhaven) ; Flores, C.E. (UC, Davis) ; Fulek, L. (AGH-UST, Cracow) ; Gagliardi, C.A. (Texas A-M) ; Garand, D. (Purdue U.) ; Geurts, F. (Rice U.) ; Gibson, A. (Valparaiso U., Indiana) ; Girard, M. (Warsaw U. of Tech.) ; Grosnick, D. (Valparaiso U., Indiana) ; Gunarathne, D.S. (Pennsylvania U.) ; Guo, Y. (Kent State U.) ; Gupta, A. (Jammu U.) ; Gupta, S. (Jammu U.) ; Guryn, W. (Brookhaven) ; Hamad, A.I. (Kent State U.) ; Hamed, A. (Texas A-M) ; Harlenderova, A. (Prague, Tech. U.) ; Harris, J.W. (Yale U.) ; He, L. (Purdue U.) ; Heppelmann, S. (Penn State U.) ; Heppelmann, S. (UC, Davis) ; Hirsch, A. (Purdue U.) ; Hoffmann, G.W. (Texas U.) ; Horvat, S. (Yale U.) ; Huang, T. (Taiwan, Natl. Cheng Kung U.) ; Huang, B. (Illinois U., Chicago) ; Huang, X. (Tsinghua U., Beijing) ; Huang, H.Z. (UCLA) ; Humanic, T.J. (Ohio State U.) ; Huo, P. (SUNY, Stony Brook) ; Igo, G. (UCLA) ; Jacobs, W.W. (Indiana U.) ; Jentsch, A. (Texas U.) ; Jia, J. (SUNY, Stony Brook) ; Jiang, K. (Hefei, CUST) ; Jowzaee, S. (Wayne State U.) ; Judd, E.G. (UC, Berkeley) ; Kabana, S. (Kent State U.) ; Kalinkin, D. (Indiana U.) ; Kang, K. (Tsinghua U., Beijing) ; Kauder, K. (Wayne State U.) ; Ke, H.W. (Brookhaven) ; Keane, D. (Kent State U.) ; Kechechyan, A. (Dubna, JINR) ; Khan, Z. (Illinois U., Chicago) ; Kikoła , D.P. (Warsaw U. of Tech.) ; Kisel, I. (Frankfurt U., FIAS) ; Kisiel, A. (Warsaw U. of Tech.) ; Kochenda, L. (Moscow Phys. Eng. Inst.) ; Kocmanek, M. (Charles U.) ; Kollegger, T. (Frankfurt U., FIAS) ; Kosarzewski, L.K. (Warsaw U. of Tech.) ; Kraishan, A.F. (Pennsylvania U.) ; Kravtsov, P. (Moscow Phys. Eng. Inst.) ; Krueger, K. (Argonne) ; Kulathunga, N. (Houston U.) ; Kumar, L. (Panjab U.) ; Kvapil, J. (Prague, Tech. U.) ; Kwasizur, J.H. (Indiana U.) ; Lacey, R. (SUNY, Stony Brook) ; Landgraf, J.M. (Brookhaven) ; Landry, K.D. (UCLA) ; Lauret, J. (Brookhaven) ; Lebedev, A. (Brookhaven) ; Lednicky, R. (Dubna, JINR) ; Lee, J.H. (Brookhaven) ; Li, X. (Hefei, CUST) ; Li, C. (Hefei, CUST) ; Li, W. (SINAP, Shanghai) ; Li, Y. (Tsinghua U., Beijing) ; Lidrych, J. (Prague, Tech. U.) ; Lin, T. (Indiana U.) ; Lisa, M.A. (Ohio State U.) ; Liu, H. (Indiana U.) ; Liu, P. (SUNY, Stony Brook) ; Liu, Y. (Texas A-M) ; Liu, F. (Hua-Zhong Normal U.) ; Ljubicic, T. (Brookhaven) ; Llope, W.J. (Wayne State U.) ; Lomnitz, M. (LBL, Berkeley) ; Longacre, R.S. (Brookhaven) ; Luo, S. (Illinois U., Chicago) ; Luo, X. (Hua-Zhong Normal U.) ; Ma, G.L. (SINAP, Shanghai) ; Ma, L. (SINAP, Shanghai) ; Ma, Y.G. (SINAP, Shanghai) ; Ma, R. (Brookhaven) ; Magdy, N. (SUNY, Stony Brook) ; Majka, R. (Yale U.) ; Mallick, D. (Bhubaneswar, NISER) ; Margetis, S. (Kent State U.) ; Markert, C. (Texas U.) ; Matis, H.S. (LBL, Berkeley) ; Meehan, K. (UC, Davis) ; Mei, J.C. (Shandong U.) ; Miller, Z.W. (Illinois U., Chicago) ; Minaev, N.G. (Serpukhov, IHEP) ; Mioduszewski, S. (Texas A-M) ; Mishra, D. (Bhubaneswar, NISER) ; Mizuno, S. (LBL, Berkeley) ; Mohanty, B. (Bhubaneswar, NISER) ; Mondal, M.M. (Bhubaneswar, Inst. Phys.) ; Morozov, D.A. (Serpukhov, IHEP) ; Mustafa, M.K. (LBL, Berkeley) ; Nasim, Md. (UCLA) ; Nayak, T.K. (Calcutta, VECC) ; Nelson, J.M. (UC, Berkeley) ; Nie, M. (SINAP, Shanghai) ; Nigmatkulov, G. (Moscow Phys. Eng. Inst.) ; Niida, T. (Wayne State U.) ; Nogach, L.V. (Serpukhov, IHEP) ; Nonaka, T. (Tsukuba U.) ; Nurushev, S.B. (Serpukhov, IHEP) ; Odyniec, G. (LBL, Berkeley) ; Ogawa, A. (Brookhaven) ; Oh, K. (Pusan Natl. U.) ; Okorokov, V.A. (Moscow Phys. Eng. Inst.) ; , D.Olvitt Jr. (Pennsylvania U.) ; Page, B.S. (Brookhaven) ; Pak, R. (Brookhaven) ; Pandit, Y. (Illinois U., Chicago) ; Panebratsev, Y. (Dubna, JINR) ; Pawlik, B. (Cracow, INP) ; Pei, H. (Hua-Zhong Normal U.) ; Perkins, C. (UC, Berkeley) ; Pile, P. (Brookhaven) ; Pluta, J. (Warsaw U. of Tech.) ; Poniatowska, K. (Warsaw U. of Tech.) ; Porter, J. (LBL, Berkeley) ; Posik, M. (Pennsylvania U.) ; Poskanzer, A.M. (LBL, Berkeley) ; Pruthi, N.K. (Panjab U.) ; Przybycien, M. (AGH-UST, Cracow) ; Putschke, J. (Wayne State U.) ; Qiu, H. (Purdue U.) ; Quintero, A. (Pennsylvania U.) ; Ramachandran, S. (U. Kentucky, Lexington) ; Ray, R.L. (Texas U.) ; Reed, R. (Lehigh U.) ; Rehbein, M.J. (Creighton U.) ; Ritter, H.G. (LBL, Berkeley) ; Roberts, J.B. (Rice U.) ; Rogachevskiy, O.V. (Dubna, JINR) ; Romero, J.L. (UC, Davis) ; Roth, J.D. (Creighton U.) ; Ruan, L. (Brookhaven) ; Rusnak, J. (Charles U.) ; Rusnakova, O. (Prague, Tech. U.) ; Sahoo, N.R. (Texas A-M) ; Sahu, P.K. (Bhubaneswar, Inst. Phys.) ; Salur, S. (LBL, Berkeley) ; Sandweiss, J. (Yale U.) ; Saur, M. (Charles U.) ; Schambach, J. (Texas U.) ; Schmah, A.M. (LBL, Berkeley) ; Schmidke, W.B. (Brookhaven) ; Schmitz, N. (Munich, Max Planck Inst.) ; Schweid, B.R. (SUNY, Stony Brook) ; Seger, J. (Creighton U.) ; Sergeeva, M. (UCLA) ; Seyboth, P. (Munich, Max Planck Inst.) ; Shah, N. (SINAP, Shanghai) ; Shahaliev, E. (Dubna, JINR) ; Shanmuganathan, P.V. (Lehigh U.) ; Shao, M. (Hefei, CUST) ; Sharma, A. (Jammu U.) ; Sharma, M.K. (Jammu U.) ; Shen, W.Q. (SINAP, Shanghai) ; Shi, Z. (LBL, Berkeley) ; Shi, S.S. (Hua-Zhong Normal U.) ; Shou, Q.Y. (SINAP, Shanghai) ; Sichtermann, E.P. (LBL, Berkeley) ; Sikora, R. (AGH-UST, Cracow) ; Simko, M. (Charles U.) ; Singha, S. (Kent State U.) ; Skoby, M.J. (Indiana U.) ; Smirnov, N. (Yale U.) ; Smirnov, D. (Brookhaven) ; Solyst, W. (Indiana U.) ; Song, L. (Houston U.) ; Sorensen, P. (Brookhaven) ; Spinka, H.M. (Argonne) ; Srivastava, B. (Purdue U.) ; Stanislaus, T.D.S. (Valparaiso U., Indiana) ; Strikhanov, M. (Moscow Phys. Eng. Inst.) ; Stringfellow, B. (Purdue U.) ; Sugiura, T. (Tsukuba U.) ; Sumbera, M. (Charles U.) ; Summa, B. (Penn State U.) ; Sun, Y. (Hefei, CUST) ; Sun, X.M. (Hua-Zhong Normal U.) ; Sun, X. (Hua-Zhong Normal U.) ; Surrow, B. (Pennsylvania U.) ; Svirida, D.N. (Moscow, ITEP) ; Tang, A.H. (Brookhaven) ; Tang, Z. (Hefei, CUST) ; Taranenko, A. (Moscow Phys. Eng. Inst.) ; Tarnowsky, T. (Michigan State U.) ; Tawfik, A. (WLCAPP, Cairo) ; Thäder, J. (LBL, Berkeley) ; Thomas, J.H. (LBL, Berkeley) ; Timmins, A.R. (Houston U.) ; Tlusty, D. (Rice U.) ; Todoroki, T. (Brookhaven) ; Tokarev, M. (Dubna, JINR) ; Trentalange, S. (UCLA) ; Tribble, R.E. (Texas A-M) ; Tribedy, P. (Brookhaven) ; Tripathy, S.K. (Bhubaneswar, Inst. Phys.) ; Trzeciak, B.A. (Prague, Tech. U.) ; Tsai, O.D. (UCLA) ; Ullrich, T. (Brookhaven) ; Underwood, D.G. (Argonne) ; Upsal, I. (Ohio State U.) ; Van Buren, G. (Brookhaven) ; van Nieuwenhuizen, G. (Brookhaven) ; Vasiliev, A.N. (Serpukhov, IHEP) ; Videbæk, F. (Brookhaven) ; Vokal, S. (Dubna, JINR) ; Voloshin, S.A. (Wayne State U.) ; Vossen, A. (Indiana U.) ; Wang, G. (UCLA) ; Wang, Y. (Hua-Zhong Normal U.) ; Wang, F. (Purdue U.) ; Wang, Y. (Tsinghua U., Beijing) ; Webb, J.C. (Brookhaven) ; Webb, G. (Brookhaven) ; Wen, L. (UCLA) ; Westfall, G.D. (Michigan State U.) ; Wieman, H. (LBL, Berkeley) ; Wissink, S.W. (Indiana U.) ; Witt, R. (Naval Academy, Annapolis) ; Wu, Y. (Kent State U.) ; Xiao, Z.G. (Tsinghua U., Beijing) ; Xie, W. (Purdue U.) ; Xie, G. (Hefei, CUST) ; Xu, J. (Hua-Zhong Normal U.) ; Xu, N. (LBL, Berkeley) ; Xu, Q.H. (Shandong U.) ; Xu, Y.F. (SINAP, Shanghai) ; Xu, Z. (Brookhaven) ; Yang, Y. (Taiwan, Natl. Cheng Kung U.) ; Yang, Q. (Hefei, CUST) ; Yang, C. (Shandong U.) ; Yang, S. (Brookhaven) ; Ye, Z. (Illinois U., Chicago) ; Ye, Z. (Illinois U., Chicago) ; Yi, L. (Yale U.) ; Yip, K. (Brookhaven) ; Yoo, I.-K. (Pusan Natl. U.) ; Yu, N. (Hua-Zhong Normal U.) ; Zbroszczyk, H. (Warsaw U. of Tech.) ; Zha, W. (Hefei, CUST) ; Zhang, Z. (SINAP, Shanghai) ; Zhang, X.P. (Tsinghua U., Beijing) ; Zhang, J.B. (Hua-Zhong Normal U.) ; Zhang, S. (Hefei, CUST) ; Zhang, J. (Lanzhou, Inst. Modern Phys.) ; Zhang, Y. (Hefei, CUST) ; Zhang, J. (LBL, Berkeley) ; Zhang, S. (SINAP, Shanghai) ; Zhao, J. (Purdue U.) ; Zhong, C. (SINAP, Shanghai) ; Zhou, L. (Hefei, CUST) ; Zhou, C. (SINAP, Shanghai) ; Zhu, X. (Tsinghua U., Beijing) ; Zhu, Z. (Shandong U.) ; Zyzak, M. (Frankfurt U., FIAS)

Pages: 21

Abstract: The extreme temperatures and energy densities generated by ultra-relativistic collisions between heavy nuclei produce a state of matter with surprising fluid properties. Non-central collisions have angular momentum on the order of 1000$\hbar$, and the resulting fluid may have a strong vortical structure that must be understood to properly describe the fluid. It is also of particular interest because the restoration of fundamental symmetries of quantum chromodynamics is expected to produce novel physical effects in the presence of strong vorticity. However, no experimental indications of fluid vorticity in heavy ion collisions have so far been found. Here we present the first measurement of an alignment between the angular momentum of a non-central collision and the spin of emitted particles, revealing that the fluid produced in heavy ion collisions is by far the most vortical system ever observed. We find that $\Lambda$ and $\overline{\Lambda}$ hyperons show a positive polarization of the order of a few percent, consistent with some hydrodynamic predictions. A previous measurement that reported a null result at higher collision energies is seen to be consistent with the trend of our new observations, though with larger statistical uncertainties. These data provide the first experimental access to the vortical structure of the "perfect fluid" created in a heavy ion collision. They should prove valuable in the development of hydrodynamic models that quantitatively connect observations to the theory of the Strong Force. Our results extend the recent discovery of hydrodynamic spin alignment to the subatomic realm.

Web-Page: http://inspirehep.net/record/1510474/files/LambdaInEventBlackBackgroundInset.png; http://inspirehep.net/record/1510474/files/STARoverview.png; http://inspirehep.net/record/1510474/files/PH.png; http://inspirehep.net/record/1510474/files/Fig1b.png; http://inspirehep.net/record/1510474/files/arXiv:1701.06657.pdf


Note: *Brief entry*; *Temporary entry*; 21 pages; 4 figures; submitted to Nature and under media embargo

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