Observation of a narrow meson with a mass of 1750 MeV which decays into two η mesons
Aide D., Binon F., Bricman C., Gouanere M., Donskov S. V., Inyakin A. V., Kakauridze D. B., Kachanov V. A., Kulik A. V., Lagnaux J. P., Lednev A. A., Mikhaiiov Yu. V., Mouthuy Th., Knapp E. A., Peigneux J. P., Prokoshkin Yu. D., Rodnov Yu. V., Sadovskii S. A., Samoilenko V. D., Sin'govskii A. V., Stroot J. P., Sugonyaev V. P., Khaustov G. V., Shagin P. M., Shtannikov A. V.
A meson with a small width which is produced in π~ρ collisions and which decays into an ηη pair has been discovered. The experiment was carried out with the GAMS-2000 multiphoton hodoscopic spectrometer in the pion beam at the Serpukhov accelerator at a momentum of 38 GeV/c. The mass of this new meson state is 1755 + 8 MeV, and its width does not exceed 50 MeV. The spin and parity are Jpc = 0+ + or, less probably, 2 + +. The isospin and G-parity are 0 +. The production cross section, aBR, has been found to be 3.5 ± 1.5 nb. The t dependence of the cross section is described by exp (bt) with a slope b = 3.8 + 1.5 (GeV/сГ2.