D ec 2 02 1 Coupled-channel analysis of the process γγ → π 0 π 0

Yury S. Surovtsev, Petr Bydžovský, Thomas Gutsche, Robert Kamiński, Valery E. Lyubovitskij, 5, 6, 7, 8 and Miroslav Nagy Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna, Russia Nuclear Physics Institute of the AS CR, 25068 Řež, Czech Republic Institut für Theoretische Physik, Universität Tübingen, Kepler Center for Astro and Particle Physics, Auf der Morgenstelle 14, D-72076 Tübingen, Germany Institute of Nuclear Physics PAS, Cracow 31342, Poland Departamento de F́ısica y Centro Cient́ıfico Tecnológico de Valparáıso-CCTVal, Universidad Técnica Federico Santa Maŕıa, Casilla 110-V, Valparáıso, Chile Millennium Institute for Subatomic Physics at the High-Energy Frontier (SAPHIR) of ANID, Fernández Concha 700, Santiago, Chile Department of Physics, Tomsk State University, 634050 Tomsk, Russia Tomsk Polytechnic University, 634050 Tomsk, Russia Institute of Physics, SAS, Bratislava 84511, Slovak Republic (Dated: January 3, 2022)