Two-jet mass distributions at the CERN proton-antiproton collider

Two-jet mass distributions have been measured as a function of centre-of-mass scattering angle for high-mass jet pairs produced in proton-antiproton collisions at the CERN collider operating at a centre-of-mass energy of 630 GeV. The agreement between QCD expectations and the experimental measurements has been used to place limits on the production cross section of an object X decaying into two jets. In particular we consider the existence of a massive colour octet of vector gauge bosons (axigluons). We exclude axigluons with a width Λ_A < 0.4m_A and a mass m_A in the range 150 < m_A < 310 GeV/c² (95% CL).