First measurements of ηc decaying into K+K−2(π+π−) and 3(π+π−)

Abstract The decays of η c to K + K − 2 ( π + π − ) and 3 ( π + π − ) are observed for the first time using a sample of 5.8 × 10 7 J / ψ events collected by the BESII detector. The product branching fractions are determined to be B ( J / ψ → γ η c ) ⋅ B ( η c → K + K − π + π − π + π − ) = ( 1.21 ± 0.32 ± 0.24 ) × 10 −4 , B ( J / ψ → γ η c ) ⋅ B ( η c → K ∗ 0 K ¯ ∗ 0 π + π − ) = ( 1.91 ± 0.64 ± 0.48 ) × 10 −4 , and B ( J / ψ → γ η c ) ⋅ B ( η c → π + π − π + π − π + π − ) = ( 2.59 ± 0.32 ± 0.47 ) × 10 −4 . The upper limit for η c → ϕ π + π − π + π − is also obtained as B ( J / ψ → γ η c ) ⋅ B ( η c → ϕ π + π − π + π − ) 6.03 × 10 −5 at the 90% confidence level.