Study of the centrally producer ππ andK <img src="/fulltext-image.asp?format=htmlnonpaginated&src=PR7622018MG84431_html\10052_2005_Article_BF01548557_TeX2GIFIE1.gif" border="0" alt=" $$\bar K$$ " /> systems at 85 and 300 GeV/c

We have studied the ππ andK <img src="/fulltext-image.asp?format=htmlnonpaginated&src=PR7622018MG84431_html\10052_2005_Article_BF01548557_TeX2GIFIE2.gif" border="0" alt=" $$\bar K$$ " /> systems centrally produced in proton proton collisions at 300 GeV/c and π⁺/p proton collisions at 85 GeV/c using the CERN Ω spectrometer. Clear evidence forS^*/f_o(975) production is observed. An analysis performed on the π⁺ π⁻ mass spectrum in the 1.0 GeV region, using a coupled channel formalism, shows that it is possible to describe theS^*/f_o(975) effect with one single resonance once interference of theS^*/f_o(975) with theS-wave background is introduced. The resultingS^*/f_o(975) parameters arem_o=979±4MeV,g_π=0.28±0.04,g_K=0.56±0.18 corresponding to a pole position on sheet II at (1001±2)−i(36±4) MeV. Evidence is also found for a structure having a mass of 1472±12 MeV and a width of 195±33 MeV.