Observation of the tensor glueball

Abstract

In the reactions p-p → π0π0, ηη, ηη′, in the mass region 1900–2400 MeV there are four relatively narrow resonances f2(1920), f2(2020), f2(2240), and f2(2300) and a broad one f2(2000). In the framework of quark combinatorics, we carry out an analysis of the decay constants for all five resonances. It is shown that the relations for the decay constants corresponding to the broad resonance f2(2000) → π0π0, ηη, ηη′ are the same as those corresponding to a glueball. An additional argument in favor of the glueball nature of f2(2000) is the fact that f2(1920), f2(2020), f2(2240), and f2(2300) fit well the q-q trajectories in the (n, M2) plane (where n is the radial quantum number), while the broad f2(2000) resonance turns out to be an unnecessary extra state for these trajectories.