Abstract
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; Jiang, 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 θπ* 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.
Highlights
Transitions between bound cc states as well as between bb states provide an excellent laboratory for studying heavy quark-antiquark dynamics at short distances
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
Summary
Transitions between bound cc states as well as between bb states provide an excellent laboratory for studying heavy quark-antiquark dynamics at short distances. The dynamics of this process can be investigated using very clean exclusive (2S) →ϩϪJ/, J/→lϩlϪ events, where l signifies either e or Investigation of this decay by Mark I2͔ found that the ϩϪ mass distribution was strongly peaked towards higher mass values, in contrast with what was expected from phase space. In a more general analysis, Cahn5͔ calculated the angular distributions in terms of partial-wave amplitudes diagonal in orbital and spin angular momentum Voloshin and Zakharov8͔ and later, in a revised analysis, Novikov and Shifman9͔ worked out the second step, the pion hadronization matrix element using current algebra, PCAC, ͑partial conservation of axial vector current, and gauge invariance They were able to derive an amplitude for this process from ‘‘first principles.’’ Interestingly, Ref. See Ref. ͓10͔ for a list of theory papers that attempt to deal with this problem
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