Evidence for light-by-light scattering in heavy-ion collisions with the ATLAS detector at the LHC
M. J. WhiteDepartment of Physics, University of Adelaide, Adelaide, AustraliaP. JacksonDepartment of Physics, University of Adelaide, Adelaide, AustraliaL. LeeDepartment of Physics, University of Adelaide, Adelaide, AustraliaA. PetridisDepartment of Physics, University of Adelaide, Adelaide, AustraliaS. P. SwiftPhysics Department, SUNY Albany, Albany, New York, USAV. JainPhysics Department, SUNY Albany, Albany, New York, USAJ. BouffardPhysics Department, SUNY Albany, Albany, New York, USAS. GuindonPhysics Department, SUNY Albany, Albany, New York, USAA. FischerPhysics Department, SUNY Albany, Albany, New York, USAR. W. MooreDepartment of Physics, University of Alberta, Edmonton, Alberta, CanadaN. DehghanianDepartment of Physics, University of Alberta, Edmonton, Alberta, CanadaJ. DassoulasDepartment of Physics, University of Alberta, Edmonton, Alberta, CanadaS. JabbarDepartment of Physics, University of Alberta, Edmonton, Alberta, CanadaX. SunDepartment of Physics, University of Alberta, Edmonton, Alberta, CanadaJ. L. PinfoldDepartment of Physics, University of Alberta, Edmonton, Alberta, CanadaD. M. GingrichDepartment of Physics, University of Alberta, Edmonton, Alberta, CanadaH. WangDepartment of Physics, University of Alberta, Edmonton, Alberta, CanadaH. Duran YildizDepartment of Physics, Ankara University, Ankara, TurkeyA. K. CiftciDepartment of Physics, Ankara University, Ankara, TurkeyO. CakirDepartment of Physics, Ankara University, Ankara, TurkeyS. KudayIstanbul Aydin University, Istanbul, TurkeyI. Turk CakirGiresun University, Faculty of Engineering, TurkeyS. SultansoyDivision of Physics, TOBB University of Economics and Technology, Ankara, TurkeyB. H. SmartLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceN. BergerLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceT. Hryn’ovaLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceR. LafayeLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceE. YatsenkoLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceS. JézéquelLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceP. MastrandreaLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceK. GrevtsovLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceT. GuilleminLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceI. Wingerter-SeezLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceA. M. BurgerLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceO. KivernykLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceN. Lorenzo MartinezLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceS. Todorova-NovaLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceJ. LevêqueUniversité Savoie Mont BlancL. Di CiaccioLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceM. DelmastroLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceI. KoletsouLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceS. EllesLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceE. SauvanLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceA. VallierLAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, FranceD. MalonHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAS. RyuHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAR. E. BlairHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAJ. MetcalfeHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAA. ParamonovHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAL. E. PriceHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAJ. S. WebsterHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAR. WangHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAT. LeCompteHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAP. van GemmerenHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAJ. ProudfootHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAR. W. StanekHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAJ. ZhangHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAS. ChekanovHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAJ. LoveHigh Energy Physics Division, Argonne National Laboratory, Argonne, Illinois, USAW. LamplDepartment of Physics, University of Arizona, Tucson, Arizona, USAP. LochDepartment of Physics, University of Arizona, Tucson, Arizona, USAS. JonesDepartment of Physics, University of Arizona, Tucson, Arizona, USAX. LeiDepartment of Physics, University of Arizona, Tucson, Arizona, USAR. LeoneDepartment of Physics, University of Arizona, Tucson, Arizona, USAK. A. JohnsDepartment of Physics, University of Arizona, Tucson, Arizona, USAM. A. ShupeDepartment of Physics, University of Arizona, Tucson, Arizona, USAE. CheuDepartment of Physics, University of Arizona, Tucson, Arizona, USAR. NayyarDepartment of Physics, University of Arizona, Tucson, Arizona, USAE. W. VarnesDepartment of Physics, University of Arizona, Tucson, Arizona, USAJ. P. RutherfoordDepartment of Physics, University of Arizona, Tucson, Arizona, USAV. VeeraraghavanDepartment of Physics, University of Arizona, Tucson, Arizona, USAA. WhiteDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAD. BullockDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAL. HeelanDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAH. Y. KimDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAG. UsaiDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAJ. AbdallahDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAS. DarmoraDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAA. FarbinDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAH. K. HadavandDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAA. R. StradlingDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAA. VartapetianDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAL. FeremengaDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAK. DeDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAJ. GriffithsDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAA. BrandtDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAN. OzturkDepartment of Physics, The University of Texas at Arlington, Arlington, Texas, USAJ. YuDepartment of Physics and Astronomy, Iowa State University, Ames, Iowa, USAP. IoannouPhysics Department, National and Kapodistrian University of Athens, Athens, GreeceK. PapageorgiouPhysics Department, National and Kapodistrian University of Athens, Athens, GreeceN. TsirintanisPhysics Department, National and Kapodistrian University of Athens, Athens, GreeceS. AngelidakisPhysics Department, National and Kapodistrian University of Athens, Athens, GreeceS. ChouridouPhysics Department, National and Kapodistrian University of Athens, Athens, GreeceC. KourkoumelisPhysics Department, National and Kapodistrian University of Athens, Athens, GreeceI. GkialasPhysics Department, National and Kapodistrian University of Athens, Athens, GreeceD. FassouliotisPhysics Department, National and Kapodistrian University of Athens, Athens, GreeceN. GiokarisPhysics Department, National and Kapodistrian University of Athens, Athens, GreeceN. BenekosPhysics Department, National Technical University of Athens, Zografou, GreeceA. KoulourisPhysics Department, National Technical University of Athens, Zografou, GreeceM. DrisPhysics Department, National Technical University of Athens, Zografou, Greece
2017en
ABI
Annotatsiya
Light-by-light scattering (γγ → γγ) is a quantum-mechanical process that is forbidden in the classical theory of electrodynamics. This reaction is accessible at the Large Hadron Collider thanks to the large electromagnetic field strengths generated by ultra-relativistic colliding lead ions. Using 480 μb−1 of lead–lead collision data recorded at a centre-of-mass energy per nucleon pair of 5.02 TeV by the ATLAS detector, here we report evidence for light-by-light scattering. A total of 13 candidate events were observed with an expected background of 2.6 ± 0.7 events. After background subtraction and analysis corrections, the fiducial cross-section of the process Pb + Pb (γγ) → Pb(∗) + Pb(∗)γγ, for photon transverse energy ET > 3 GeV, photon absolute pseudorapidity |η| < 2.4, diphoton invariant mass greater than 6 GeV, diphoton transverse momentum lower than 2 GeV and diphoton acoplanarity below 0.01, is measured to be 70 ± 24 (stat.) ± 17 (syst.) nb, which is in agreement with the standard model predictions. Quantum electrodynamics predicts a rare process in which light is scattered by light. The ATLAS Collaboration reports signs of this elusive effect in the collisions of ultra-relativistic lead ions.
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