APS » Phys. Rev. Lett. » Volume 102 » Issue 11

B. I. Abelev,⁹ M. M. Aggarwal,³¹ Z. Ahammed,⁴⁷ B. D. Anderson,¹⁹ D. Arkhipkin,¹³ G. S. Averichev,¹² Y. Bai,²⁸ J. Balewski,²³ O. Barannikova,⁹ L. S. Barnby,² J. Baudot,¹⁷ S. Baumgart,⁵² D. R. Beavis,³ R. Bellwied,⁵⁰ F. Benedosso,²⁸ M. J. Betancourt,²³ R. R. Betts,⁹ S. Bhardwaj,³⁶ A. Bhasin,¹⁸ A. K. Bhati,³¹ H. Bichsel,⁴⁹ J. Bielcik,¹¹ J. Bielcikova,¹¹ B. Biritz,⁶ L. C. Bland,³ M. Bombara,² B. E. Bonner,³⁷ M. Botje,²⁸ J. Bouchet,¹⁹ E. Braidot,²⁸ A. V. Brandin,²⁶ E. Bruna,⁵² S. Bueltmann,³⁰ T. P. Burton,² M. Bystersky,¹¹ X. Z. Cai,⁴⁰ H. Caines,⁵² M. Calderón de la Barca Sánchez,⁵ J. Callner,⁹ O. Catu,⁵² D. Cebra,⁵ R. Cendejas,⁶ M. C. Cervantes,⁴² Z. Chajecki,²⁹ P. Chaloupka,¹¹ S. Chattopadhyay,⁴⁷ H. F. Chen,³⁹ J. H. Chen,⁴⁰ J. Y. Chen,⁵¹ J. Cheng,⁴⁴ M. Cherney,¹⁰ A. Chikanian,⁵² K. E. Choi,³⁵ W. Christie,³ S. U. Chung,³ R. F. Clarke,⁴² M. J. M. Codrington,⁴² J. P. Coffin,¹⁷ R. Corliss,²³ T. M. Cormier,⁵⁰ M. R. Cosentino,³⁸ J. G. Cramer,⁴⁹ H. J. Crawford,⁴ D. Das,⁵ S. Dash,¹⁴ M. Daugherity,⁴³ C. De Silva,⁵⁰ T. G. Dedovich,¹² M. DePhillips,³ A. A. Derevschikov,³³ R. Derradi de Souza,⁷ L. Didenko,³ P. Djawotho,⁴² S. M. Dogra,¹⁸ X. Dong,²² J. L. Drachenberg,⁴² J. E. Draper,⁵ F. Du,⁵² J. C. Dunlop,³ M. R. Dutta Mazumdar,⁴⁷ W. R. Edwards,²² L. G. Efimov,¹² E. Elhalhuli,² M. Elnimr,⁵⁰ V. Emelianov,²⁶ J. Engelage,⁴ G. Eppley,³⁷ B. Erazmus,⁴¹ M. Estienne,¹⁷ L. Eun,³² P. Fachini,³ R. Fatemi,²⁰ J. Fedorisin,¹² A. Feng,⁵¹ P. Filip,¹³ E. Finch,⁵² V. Fine,³ Y. Fisyak,³ C. A. Gagliardi,⁴² L. Gaillard,² D. R. Gangadharan,⁶ M. S. Ganti,⁴⁷ E. Garcia-Solis,⁹ V. Ghazikhanian,⁶ P. Ghosh,⁴⁷ Y. N. Gorbunov,¹⁰ A. Gordon,³ O. Grebenyuk,²² D. Grosnick,⁴⁶ B. Grube,³⁵ S. M. Guertin,⁶ K. S. F. F. Guimaraes,³⁸ A. Gupta,¹⁸ N. Gupta,¹⁸ W. Guryn,³ B. Haag,⁵ T. J. Hallman,³ A. Hamed,⁴² J. W. Harris,⁵² W. He,¹⁶ M. Heinz,⁵² S. Heppelmann,³² B. Hippolyte,¹⁷ A. Hirsch,³⁴ E. Hjort,²² A. M. Hoffman,²³ G. W. Hoffmann,⁴³ D. J. Hofman,⁹ R. S. Hollis,⁹ H. Z. Huang,⁶ T. J. Humanic,²⁹ G. Igo,⁶ A. Iordanova,⁹ P. Jacobs,²² W. W. Jacobs,¹⁶ P. Jakl,¹¹ F. Jin,⁴⁰ C. L. Jones,²³ P. G. Jones,² J. Joseph,¹⁹ E. G. Judd,⁴ S. Kabana,⁴¹ K. Kajimoto,⁴³ K. Kang,⁴⁴ J. Kapitan,¹¹ M. Kaplan,⁸ D. Keane,¹⁹ A. Kechechyan,¹² D. Kettler,⁴⁹ V. Yu. Khodyrev,³³ D. P. Kikola,²² J. Kiryluk,²² A. Kisiel,²⁹ S. R. Klein,²² A. G. Knospe,⁵² A. Kocoloski,²³ D. D. Koetke,⁴⁶ M. Kopytine,¹⁹ L. Kotchenda,²⁶ V. Kouchpil,¹¹ P. Kravtsov,²⁶ V. I. Kravtsov,³³ K. Krueger,¹ M. Krus,¹¹ C. Kuhn,¹⁷ L. Kumar,³¹ P. Kurnadi,⁶ M. A. C. Lamont,³ J. M. Landgraf,³ S. LaPointe,⁵⁰ J. Lauret,³ A. Lebedev,³ R. Lednicky,¹³ C-H. Lee,³⁵ W. Leight,²³ M. J. LeVine,³ C. Li,³⁸ N. Li,⁵¹ Y. Li,⁴⁴ G. Lin,⁵² S. J. Lindenbaum,²⁷ M. A. Lisa,²⁹ F. Liu,⁵¹ H. Liu,⁵ J. Liu,³⁷ L. Liu,⁵¹ T. Ljubicic,³ W. J. Llope,³⁷ R. S. Longacre,³ W. A. Love,³ Y. Lu,³⁹ T. Ludlam,³ D. Lynn,³ G. L. Ma,⁴⁰ Y. G. Ma,⁴⁰ D. P. Mahapatra,¹⁴ R. Majka,⁵² O. I. Mall,⁵ L. K. Mangotra,¹⁸ R. Manweiler,⁴⁶ S. Margetis,¹⁹ C. Markert,⁴³ H. S. Matis,²² Yu. A. Matulenko,³³ T. S. McShane,¹⁰ A. Meschanin,³³ R. Milner,²³ N. G. Minaev,³³ S. Mioduszewski,⁴² A. Mischke,²⁸ J. Mitchell,³⁷ B. Mohanty,⁴⁷ D. A. Morozov,³³ M. G. Munhoz,³⁸ B. K. Nandi,¹⁵ C. Nattrass,⁵² T. K. Nayak,⁴⁷ J. M. Nelson,² C. Nepali,¹⁹ P. K. Netrakanti,³⁴ M. J. Ng,⁴ L. V. Nogach,³³ S. B. Nurushev,³³ G. Odyniec,²² A. Ogawa,³ H. Okada,³ V. Okorokov,²⁶ D. Olson,²² M. Pachr,¹¹ B. S. Page,¹⁶ S. K. Pal,⁴⁷ Y. Pandit,¹⁹ Y. Panebratsev,¹² T. Pawlak,⁴⁸ T. Peitzmann,²⁸ V. Perevoztchikov,³ C. Perkins,⁴ W. Peryt,⁴⁸ S. C. Phatak,¹⁴ M. Planinic,⁵³ J. Pluta,⁴⁸ N. Poljak,⁵³ A. M. Poskanzer,²² B. V. K. S. Potukuchi,¹⁸ D. Prindle,⁴⁹ C. Pruneau,⁵⁰ N. K. Pruthi,³¹ J. Putschke,⁵² R. Raniwala,³⁶ S. Raniwala,³⁶ R. L. Ray,⁴³ R. Redwine,²³ R. Reed,⁵ A. Ridiger,²⁶ H. G. Ritter,²² J. B. Roberts,³⁷ O. V. Rogachevskiy,¹² J. L. Romero,⁵ A. Rose,²² C. Roy,⁴¹ L. Ruan,³ M. J. Russcher,²⁸ V. Rykov,¹⁹ R. Sahoo,⁴¹ I. Sakrejda,²² T. Sakuma,²³ S. Salur,²² J. Sandweiss,⁵² M. Sarsour,⁴² J. Schambach,⁴³ R. P. Scharenberg,³⁴ N. Schmitz,²⁴ J. Seger,¹⁰ I. Selyuzhenkov,¹⁶ P. Seyboth,²⁴ A. Shabetai,¹⁷ E. Shahaliev,¹² M. Shao,³⁹ M. Sharma,⁵⁰ S. S. Shi,⁵¹ X-H. Shi,⁴⁰ E. P. Sichtermann,²² F. Simon,²⁴ R. N. Singaraju,⁴⁷ M. J. Skoby,³⁴ N. Smirnov,⁵² R. Snellings,²⁸ P. Sorensen,³ J. Sowinski,¹⁶ H. M. Spinka,¹ B. Srivastava,³⁴ A. Stadnik,¹² T. D. S. Stanislaus,⁴⁶ D. Staszak,⁶ M. Strikhanov,²⁶ B. Stringfellow,³⁴ A. A. P. Suaide,³⁸ M. C. Suarez,⁹ N. L. Subba,¹⁹ M. Sumbera,¹¹ X. M. Sun,²² Y. Sun,³⁹ Z. Sun,²¹ B. Surrow,²³ T. J. M. Symons,²² A. Szanto de Toledo,³⁸ J. Takahashi,⁷ A. H. Tang,³ Z. Tang,³⁹ T. Tarnowsky,³⁴ D. Thein,⁴³ J. H. Thomas,²² J. Tian,⁴⁰ A. R. Timmins,² S. Timoshenko,²⁶ D. Tlusty,¹¹ M. Tokarev,¹² T. A. Trainor,⁴⁹ V. N. Tram,²² A. L. Trattner,⁴ S. Trentalange,⁶ R. E. Tribble,⁴² O. D. Tsai,⁶ J. Ulery,³⁴ T. Ullrich,³ D. G. Underwood,¹ G. Van Buren,³ M. van Leeuwen,²⁸ A. M. Vander Molen,²⁵ J. A. Vanfossen, Jr.,¹⁹ R. Varma,¹⁵ G. M. S. Vasconcelos,⁷ I. M. Vasilevski,¹³ A. N. Vasiliev,³³ F. Videbaek,³ S. E. Vigdor,¹⁶ Y. P. Viyogi,¹⁴ S. Vokal,¹² S. A. Voloshin,⁵⁰ M. Wada,⁴³ W. T. Waggoner,¹⁰ M. Walker,²³ F. Wang,³⁴ G. Wang,⁶ J. S. Wang,²¹ Q. Wang,³⁴ X. Wang,⁴⁴ X. L. Wang,³⁹ Y. Wang,⁴⁴ J. C. Webb,⁴⁶ G. D. Westfall,²⁵ C. Whitten, Jr.,⁶ H. Wieman,²² S. W. Wissink,¹⁶ R. Witt,⁴⁵ Y. Wu,⁵¹ W. Xie,³⁴ N. Xu,²² Q. H. Xu,²² Y. Xu,³⁹ Z. Xu,³ P. Yepes,³⁷ I-K. Yoo,³⁵ Q. Yue,⁴⁴ M. Zawisza,⁴⁸ H. Zbroszczyk,⁴⁸ W. Zhan,²¹ H. Zhang,³ S. Zhang,⁴⁰ W. M. Zhang,¹⁹ Y. Zhang,³⁹ Z. P. Zhang,³⁹ Y. Zhao,³⁹ C. Zhong,⁴⁰ J. Zhou,³⁷ R. Zoulkarneev,¹³ Y. Zoulkarneeva,¹³ and J. X. Zuo⁴⁰

(STAR Collaboration)

¹Argonne National Laboratory, Argonne, Illinois 60439, USA
²University of Birmingham, Birmingham, United Kingdom
³Brookhaven National Laboratory, Upton, New York 11973, USA
⁴University of California, Berkeley, California 94720, USA
⁵University of California, Davis, California 95616, USA
⁶University of California, Los Angeles, California 90095, USA
⁷Universidade Estadual de Campinas, Sao Paulo, Brazil
⁸Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
⁹University of Illinois at Chicago, Chicago, Illinois 60607, USA
¹⁰Creighton University, Omaha, Nebraska 68178, USA
¹¹Nuclear Physics Institute AS CR, 250 68 Řež/Prague, Czech Republic
¹²Laboratory for High Energy (JINR), Dubna, Russia
¹³Particle Physics Laboratory (JINR), Dubna, Russia
¹⁴Institute of Physics, Bhubaneswar 751005, India
¹⁵Indian Institute of Technology, Mumbai, India
¹⁶Indiana University, Bloomington, Indiana 47408, USA
¹⁷Institut de Recherches Subatomiques, Strasbourg, France
¹⁸University of Jammu, Jammu 180001, India
¹⁹Kent State University, Kent, Ohio 44242, USA
²⁰University of Kentucky, Lexington, Kentucky, 40506-0055, USA
²¹Institute of Modern Physics, Lanzhou, China
²²Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
²³Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
²⁴Max-Planck-Institut für Physik, Munich, Germany
²⁵Michigan State University, East Lansing, Michigan 48824, USA
²⁶Moscow Engineering Physics Institute, Moscow, Russia
²⁷City College of New York, New York, New York 10031, USA
²⁸NIKHEF and Utrecht University, Amsterdam, The Netherlands
²⁹Ohio State University, Columbus, Ohio 43210, USA
³⁰Old Dominion University, Norfolk, Virginia, 23529, USA
³¹Panjab University, Chandigarh 160014, India
³²Pennsylvania State University, University Park, Pennsylvania 16802, USA
³³Institute of High Energy Physics, Protvino, Russia
³⁴Purdue University, West Lafayette, Indiana 47907, USA
³⁵Pusan National University, Pusan, Republic of Korea
³⁶University of Rajasthan, Jaipur 302004, India
³⁷Rice University, Houston, Texas 77251, USA
³⁸Universidade de Sao Paulo, Sao Paulo, Brazil
³⁹University of Science and Technology of China, Hefei 230026, China
⁴⁰Shanghai Institute of Applied Physics, Shanghai 201800, China
⁴¹SUBATECH, Nantes, France
⁴²Texas A&M University, College Station, Texas 77843, USA
⁴³University of Texas, Austin, Texas 78712, USA
⁴⁴Tsinghua University, Beijing 100084, China
⁴⁵United States Naval Academy, Annapolis, Maryland 21402, USA
⁴⁶Valparaiso University, Valparaiso, Indiana 46383, USA
⁴⁷Variable Energy Cyclotron Center, Kolkata 700064, India
⁴⁸Warsaw University of Technology, Warsaw, Poland
⁴⁹University of Washington, Seattle, Washington 98195, USA
⁵⁰Wayne State University, Detroit, Michigan 48201, USA
⁵¹Institute of Particle Physics, CCNU (HZNU), Wuhan 430079, China
⁵²Yale University, New Haven, Connecticut 06520, USA
⁵³University of Zagreb, Zagreb, HR-10002, Croatia

In ultraperipheral relativistic heavy-ion collisions, a photon from the electromagnetic field of one nucleus can fluctuate to a quark-antiquark pair and scatter from the other nucleus, emerging as a ⁰. The ⁰ production occurs in two well-separated (median impact parameters of 20 and 40 F for the cases considered here) nuclei, so the system forms a two-source interferometer. At low transverse momenta, the two amplitudes interfere destructively, suppressing ⁰ production. Since the ⁰ decays before the production amplitudes from the two sources can overlap, the two-pion system can only be described with an entangled nonlocal wave function, and is thus an example of the Einstein-Podolsky-Rosen paradox. We observe this suppression in 200 GeV per nucleon-pair gold-gold collisions. The interference is 87%±5%(stat.)±8%(syst.) of the expected level. This translates into a limit on decoherence due to wave function collapse or other factors of 23% at the 90% confidence level.

©2009 The American Physical Society

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