Dynamics of a periodic XY chain coupled to a photon mode Stanislav Varbev, Iavor Boradjiev, Hristo Tonchev and Hassan Chamati Eur. Phys. J. B, 93 7 (2020) 131 Published online: 13 July 2020 DOI: 10.1140/epjb/e2020-10262-7