Electromagnetic vacuum fluctuations around a cosmic string in de Sitter spacetime A. A. Saharian, V. F. Manukyan and N. A. Saharyan Eur. Phys. J. C, 77 7 (2017) 478 Published online: 18 July 2017 DOI: 10.1140/epjc/s10052-017-5047-7