1999/09/23 by J. Z. Bai, Y. Ban, J. G. Bian +97 · 67 citations
Physics and Astronomy · #Amplitude #Angular momentum #Distribution (mathematics) #Function (biology) #High-Energy Particle Collisions Research #Momentum (technical analysis) #Particle physics theoretical and experimental studies #Pion #Quantum Chromodynamics and Particle Interactions #Quarkonium #hep-ex
paper · pdf · doi:10.1103/physrevd.62.032002
published in Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields 62(3) (American Physical Society) · 21 pages, 10 figures
arxiv created 1999/09/23 · openalex publication_date 2000/07/05 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Using a sample of 3.8 M \ensuremathψ(2S) events accumulated with the BES detector, the process \ensuremathψ(2S)\ensuremath→\ensuremathπ+\ensuremathπ^\ensuremath-J/\ensuremathψ 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/\ensuremathψ\ensuremath-(\ensuremathπ+\ensuremathπ^\ensuremath-) 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 \ensuremathκ, predicts that D wave pions should be present. We determine \ensuremathκ=0.183\ifmmode±\else\textpm\fi0.002\ifmmode±\else\textpm\fi0.003 based on the joint m_\ensuremathπ\ensuremathπ\ensuremath-cos\ensuremathθ_\ensuremathπ* distribution. The fraction of D wave amplitude as a function of m_\ensuremathπ\ensuremathπ is found to decrease with increasing m_\ensuremathπ\ensuremathπ, in agreement with the model. We have also fit the Mannel-Yan model, which is another model that allows D wave pions.