The BRST-invariant vacuum state of the Gribov–Zwanziger theory D. Dudal, C. P. Felix, L. F. Palhares, F. Rondeau and D. Vercauteren Eur. Phys. J. C, 79 9 (2019) 731 Published online: 31 August 2019 DOI: 10.1140/epjc/s10052-019-7235-0