New exclusion limits for dark gauge forces from beam-dump data

We re-analyze published proton beam dump data taken at the U70 accelerator at IHEP Serpukhov with the ν-calorimeter I experiment in 1989 to set mass-coupling limits for dark gauge forces. The corresponding data have been used for axion and light Higgs particle searches in Blümlein et al. (1991, 1992) [1], [2] before. We determine new mass and coupling exclusion bounds for dark gauge bosons.