Analysis Of ψ(3686)→γΠ~+Π~-Π~0 And ψ(3686)→(?)K_S~0∧+c.c. On BES Ⅲ

As the lowest-lying pseudoscalar cc state, the ηc meson has attracted considerable theoret-ical and experimental attention since it was discovered by SPERA three decades ago.According to the theory of Quantum Chromodynamics(QCD), the ηc meson decays through cc annihilation into two gluons. Hence much information on gluon dynamics can be obtained by studying ηc decays. Using a sample of 4.48 × 108 ψ(3686) events collected with the BESⅢ detector, a search for the isospin violating decay ψ(3686) → γηc with ηc → π+π-π0 is presented. No signal is observed, and the upper limit on B(ψ(3686) → γηc → γπ+π-π0) is determined to be 1.6 × 10-6 at the 90% confidence level using the Bayesian method.Then, with the same final state γπ+π-π0, this paper also studied the decay chan-nels ψ(3686) → γf0(980)π0,f0(980) → π+π- and ψ(3686) → γη(1405), η(1405) →f0(980)π0, f0(980) → π+π-. The branching fraction of the former is:B(ψ(3686) →γf0(980)π0,f0(980) → π+π-) = (1.15 ± 0.30 (stat) ± 0.07 (syst)) × 10-6;Since there was no obvious signal of η(1405) observed in the later decay channel, the upper limit on the product branching fraction of it is given at 90% confidence level:B(ψ(3686) → γη(1405), η(1405) → f0(980)π0,f0(980) → π+π-) < 4.9 × 10-7.At last, this paper performed a analysis to the decay channel ψ(3686) → nKS0Λ + c.c. It is designed to study the resonance state in the particle combination of final states, the method used is partial wave analysis(PWA) of FDC. A clean sample of ψ(3686) → nKS0Λ + c.c. is selected, and one PWA baseline solution including the resonances of Λ(1520), Λ(1600), Λ(1690), Λ(1810)and N(2300) is given. However, there are many problems that are not resolved. The analysis continues.