ψ(2S)→π+π- J/ψ decay distributions

Author(s): Bai, JZ; Ban, Y; Bian, JG; Blum, I; Chen, GP; Chen, HF; Chen, J; Chen, JC; Chen, Y; Chen, YB; Chen, YQ; Cheng, BS; Cui, XZ; Ding, HL; Dong, LY; Du, ZZ; Dunwoodie, W; Gao, CS; Gao, ML; Gao, SQ; Gratton, P; Gu, JH; Gu, SD; Gu, WX; Gu, YF; Guo, ZJ; Guo, YN; Han, SW; Han, Y; Harris, FA; He, J; He, JT; He, KL; He, M; Heng, YK; Hitlin, DG; Hu, GY; Hu, HM; Hu, JL; Hu, QH; Hu, T; Hu, XQ; Huang, GS; Huang, YZ; Izen, JM; Jiana, CH; Jin, Y; Jones, BD; Ju, X; Ke, ZJ; Kelsey, MH; Kim, BK; Kong, D; Lai, YF; Lang, PF; Lankford, A; Li, CG; Li, D; Li, HB; Li, J; Li, JC; Li, PQ; Li, RB; Li, W; Li, WG; Li, XH; Li, XN; Liu, HM; Liu, J; Liu, RG; Liu, Y; Lou, XC; Lowery, B; Lu, F; Lu, JG; Luo, XL; Ma, EC; Ma, JM; Malchow, R; Mao, HS; Mao, ZP; Meng, XC; Nie, J; Olsen, SL; Oyang, J | Abstract: Using a sample of 3.8 M ψ(2S) events accumulated with the BES detector, the process ψ(2S) → π+π- J/ψ is studied. The angular distributions are compared with the general decay amplitude analysis of Cahn. We find that the dipion system requires some D wave amplitude, as well as S wave. On the other hand, the J/ψ-(π+π-) relative angular momentum is consistent with being pure S wave. The decay distributions have been fit to heavy quarkonium models, including the Novikov-Shifman model. This model, which is written in terms of the parameter κ, predicts that D wave pions should be present. We determine κ=0.183 ±0.002±0.003 based on the joint mππ-cos θ*π distribution. The fraction of D wave amplitude as a function of mππ is found to decrease with increasing mππ, in agreement with the model. We have also fit the Mannel-Yan model, which is another model that allows D wave pions. ©2000 The American Physical Society.