PT Journal
AU ATLAS Collaboration (Aaboud, Mea
   Alvarez Piqueras, D
   Barranco Navarro, L
   Cabrera Urban, S
   Castillo Gimenez, V
   Cerda Alberich, L
   Costa, MJ
   Fernandez Martinez, P
   Ferrer, A
   Fiorini, L
   Fuster, J
   Garcia, C
   Garcia Navarro, JE
   Gonzalez de la Hoz, S
   Higon-Rodriguez, E
   Jimenez Pena, J
   Lacasta, C
   Mamuzic, J
   Marti-Garcia, S
   Melini, D
   Mitsou, VA
   Pedraza Lopez, S
   Rodriguez Rodriguez, D
   Romero Adam, E
   Salt, J
   Sanchez Martinez, V
   Soldevila, U
   Sanchez, J
   Valero, A
   Valls Ferrer, JA
   Vos, M
TI Evidence for light-by-light scattering in heavy-ion collisions with the ATLAS detector at the LHC
SO Nature Physics
JI Nat. Phys.
PY 2017
BP 852
EP 858
VL 13
IS 9
DI 10.1038/NPHYS4208
LA English
AB Light-by-light scattering (gamma gamma -> gamma gamma) 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 (gamma gamma) -> Pb-(center dot) + Pb-(center dot) gamma gamma, for photon transverse energy E-T > 3 GeV, photon absolute pseudorapidity vertical bar eta vertical bar < 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.
ER