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作者机构:University of Birmingham Birmingham United Kingdom Panjab University Chandigarh 160014 India Variable Energy Cyclotron Centre Kolkata 700064 India Kent State University Kent Ohio 44242 USA Particle Physics Laboratory (JINR) Dubna Russia Laboratory for High Energy (JINR) Dubna Russia NIKHEF Amsterdam The Netherlands Indiana University Bloomington Indiana 47408 USA Purdue University West Lafayette Indiana 47907 USA Institut de Recherches Subatomiques Strasbourg France Ohio State University Columbus Ohio 43210 USA Wayne State University Detroit Michigan 48201 USA University of Frankfurt Frankfurt Germany Yale University New Haven Connecticut 06520 USA University of Rajasthan Jaipur 302004 India University of Washington Seattle Washington 98195 USA Brookhaven National Laboratory Upton New York 11973 USA Rice University Houston Texas 77251 USA SUBATECH Nantes France Moscow Engineering Physics Institute Moscow Russia Nuclear Physics Institute AS CR 250 68 Řež/Prague Czech Republic Argonne National Laboratory Argonne Illinois 60439 USA Shanghai Institute of Applied Physics Shanghai 201800 People’s Republic of China Lawrence Berkeley National Laboratory Berkeley California 94720 USA University of California Davis California 95616 USA Warsaw University of Technology Warsaw Poland University of Science & Technology of China Anhui 230027 China University of California Los Angeles California 90095 USA Tsinghua University Beijing People’s Republic of China Creighton University Omaha Nebraska 68178 USA University of California Berkeley California 94720 USA Universidade de Sao Paulo Sao Paulo Brazil Institute of High Energy Physics Protvino Russia Insitute of Physics Bhubaneswar 751005 India Max-Planck-Institut für Physik Munich Germany Texas A & M University College Station Texas 77843 USA Valparaiso University Valparaiso Indiana 46383 USA University of Jammu Jammu 180001 India Pennsylvania State University University Park Pennsylvania 16802 USA University of Texas Austin Texas 78712 USA California Institute of Technology Pasedena California 91125 USA Carnegie Mellon University Pittsburgh Pennsylvania 15213 USA Massachusetts Institute of Technology Cambridge Massachusetts 02139-4307 USA City College of New York New York City New York 10031 USA Institute of Particle Physics CCNU (HZNU) Wuhan 430079 China University of Zagreb Zagreb HR-10002 Croatia Michigan State University East Lansing Michigan 48824 USA Indian Institute of Technology Mumbai India
出 版 物:《Physical Review C》 (物理学评论C辑:核物理学)
年 卷 期:2004年第70卷第3期
页 面:031902(R)-031902(R)页
核心收录:
学科分类:07[理学] 070202[理学-粒子物理与原子核物理] 0702[理学-物理学]
主 题:TIME PROJECTION CHAMBER GAMMA-GAMMA COLLIDERS PHOTON
摘 要:We present data on e+e− pair production accompanied by nuclear breakup in ultraperipheral gold-gold collisions at a center of mass energy of 200GeV per nucleon pair. The nuclear breakup requirement selects events at small impact parameters, where higher-order diagrams for pair production should be enhanced. We compare the data with two calculations: one based on the equivalent photon approximation, and the other using lowest-order quantum electrodynamics (QED). The data distributions agree with both calculations, except that the pair transverse momentum spectrum disagrees with the equivalent photon approach. We set limits on higher-order contributions to the cross section.