Evidence of Spin-Interference Effects in Exclusive Photoproduction in Ultraperipheral Heavy-Ion Collisions
B. E. Aboona58, J. Adam17, L. Adamczyk3, I. Aggarwal45, M. M. Aggarwal45, Z. Ahammed66, A. K. Alshammri33, E. C. Aschenauer7, S. Aslam22 et al. (STAR Collaboration)
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- 1Academia Sinica, Nankang 115
- 2Abilene Christian University, Abilene, Texas 79699
- 3AGH University of Krakow, FPACS, Cracow 30-059, Poland
- 4Argonne National Laboratory, Argonne, Illinois 60439
- 5American University in Cairo, New Cairo 11835, Egypt
- 6Ball State University, Muncie, Indiana 47306
- 7Brookhaven National Laboratory, Upton, New York 11973
- 8University of Calabria & INFN-Cosenza, Rende 87036, Italy
- 9University of California, Berkeley, California 94720
- 10University of California, Davis, California 95616
- 11University of California, Los Angeles, California 90095
- 12University of California, Riverside, California 92521
- 13Central China Normal University, Wuhan, Hubei 430079
- 14University of Illinois at Chicago, Chicago, Illinois 60607
- 15Chongqing University, Chongqing 401331
- 16Creighton University, Omaha, Nebraska 68178
- 17Czech Technical University in Prague, FNSPE, Prague 115 19, Czech Republic
- 18Technische Universität Darmstadt, Darmstadt 64289, Germany
- 19National Institute of Technology Durgapur, Durgapur - 713209, India
- 20ELTE Eötvös Loránd University, Budapest H-1117, Hungary
- 21Frankfurt Institute for Advanced Studies FIAS, Frankfurt 60438, Germany
- 22Fudan University, Shanghai 200433
- 23Guangxi Normal University, Guilin 541004
- 24University of Heidelberg, Heidelberg 69120, Germany
- 25University of Houston, Houston, Texas 77204
- 26Huzhou University, Huzhou, Zhejiang 313000
- 27Indian Institute of Science Education and Research (IISER), Berhampur 760010, India
- 28Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati 517507, India
- 29Indian Institute Technology, Patna, Bihar 801106, India
- 30Indiana University, Bloomington, Indiana 47408
- 31Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, Gansu 730000
- 32University of Jammu, Jammu 180001, India
- 33Kent State University, Kent, Ohio 44242
- 34University of Kentucky, Lexington, Kentucky 40506-0055
- 35Lanzhou University, Lanzhou 730000
- 36Lawrence Berkeley National Laboratory, Berkeley, California 94720
- 37Lehigh University, Bethlehem, Pennsylvania 18015
- 38Lovely Professional University, Jalandhar - Delhi G.T. Road, Pagwara, Panjab 144411, India
- 39Max-Planck-Institut für Physik, Munich 80805, Germany
- 40Michigan State University, East Lansing, Michigan 48824
- 41National Institute of Science Education and Research, HBNI, Jatni 752050, India
- 42National Cheng Kung University, Tainan 70101
- 43Nuclear Physics Institute of the CAS, Rez 250 68, Czech Republic
- 44The Ohio State University, Columbus, Ohio 43210
- 45Panjab University, Chandigarh 160014, India
- 46Purdue University, West Lafayette, Indiana 47907
- 47Rice University, Houston, Texas 77251
- 48Rutgers University, Piscataway, New Jersey 08854
- 49University of Science and Technology of China, Hefei, Anhui 230026
- 50South China Normal University, Guangzhou, Guangdong 510631
- 51Sejong University, Seoul 05006, Republic of Korea
- 52Shandong University, Qingdao, Shandong 266237
- 53Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800
- 54Southern Connecticut State University, New Haven, Connecticut 06515
- 55State University of New York, Stony Brook, New York 11794
- 56Instituto de Alta Investigación, Universidad de Tarapacá, Arica 1000000, Chile
- 57Temple University, Philadelphia, Pennsylvania 19122
- 58Texas A&M University, College Station, Texas 77843
- 59Texas Southern University, Houston, Texas 77004
- 60University of Texas, Austin, Texas 78712
- 61Tsinghua University, Beijing 100084
- 62University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
- 63University of Chinese Academy of Sciences, Beijing 101408
- 64United States Naval Academy, Annapolis, Maryland 21402
- 65Valparaiso University, Valparaiso, Indiana 46383
- 66Variable Energy Cyclotron Centre, Kolkata 700064, India
- 67Warsaw University of Technology, Warsaw 00-661, Poland
- 68Wayne State University, Detroit, Michigan 48201
- 69Wuhan University of Science and Technology, Wuhan, Hubei 430065
- 70Yale University, New Haven, Connecticut 06520
Phys. Rev. Lett. 136, 242302 – Published 17 June, 2026
DOI: https://doi.org/10.1103/tcdb-ldh8
Abstract
We report the first evidence of spin interference in exclusive photoproduction in ultraperipheral heavy-ion collisions at STAR at . In collisions, a negative modulation is found for with a significance of , while the isobar data (, ) show a consistent negative modulation with a significance of , opposite in sign to that in photoproduction. This establishes for the first time that the interference sign is controlled by the spin structure of the final-state daughters, resolving the ambiguity present in the all-boson channel. The compact probes gluon distributions at perturbative scales, resulting in a weaker modulation and providing stringent constraints on color glass condensate calculations. These findings demonstrate that spin-dependent interference in heavy vector mesons provides a new, experimentally accessible handle on gluon structure beyond traditional cross-section measurements.