2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/231125We have found a nilpotent quantum symmetry of Yang-Mills theory restricted to the Gribov region. In fact, we give a set of transformations for the filds a la BRST that leaves the Gribov-Zwanziger action invariant and obeys the nilpotency, although the usual BRST symmetry is broken due to the non-vanishing Gribov parameter representing the presence of the Gribov horizon in the configuration space of the Yang-Mills field. We show that the horizon condition (the gap equation determining the Gribov parameter) follows from the modified BRST invariance of the vacuum.13 pages, no figure, The explicit form for F in the modified BRST transformation is changed, see eq.(3.23)to(3.27). Some comments are added in the final partHigh Energy Physics - TheoryHigh Energy Physics - Phenomenologytext