Experimental indications for a 2++ non-qq object

Abstract Using our high-statistics data from the π p → ππ n reaction, we have remade a model-independent partial-wave analysis in finer mass bins at low four-momentum transfer. The Breit-Wigner fits to the leading waves yield m ρ = (777.4 ± 2.0) MeV and Γ ρ = (160 P +4.1 −4.0 ) MeV, as well as m f = (1273.3 ± 2.3) MeV, Γ f = (179.2 +6.9 −6.6 ) MeV and x f = (84.9 ± 2.5)%. The last two parameters yield Γ (f → ππ ) = (152.1 ± 7.3) MeV, a value which is higher than the one resulting from fits to the decays of the J PC = 2 ++ mesons. On the basis of a smaller discrepancy, Rosner has speculated about a non- q q admixture (possibly gg) in the f(1270), i.e. | f (1270)〉 = | q q 〉 cos θ + | gg 〉 sin θ . Repeating his fits with more recent data we obtain a considerably more significant effect with sin 2 θ = 0.18 ± 0.04. This sets a mass of an orthogonal state | f T 〉 = − | q q 〉 sin θ + | gg 〉 cos θ between 1420 and 1620 MeV. The f T could be identified with a 1440 MeV state seen in some K K experiments, A 1 exchange being a possible production mechanism. A fit to our polarized target K + K − data at ∼ 18 GeV/ c yields m (f T ) = (1445 +20 −19 ) MeV and Γ (f T = (81 +52 −25 ) MeV.