On the failure of the 12% rule in J/ψ and ψ(2S) decays
Abstract
The 12% rule relates hadronic decays of the J/ψ and ψ(2S) through the ratio of their wave functions at the origin, but is strongly violated in several vector--pseudoscalar (VP) channels, most prominently in the ρπ one. We study these decays within an effective chiral framework including strong and electromagnetic interactions, with the latter implemented through vector meson dominance. The ψ(2S)→ VP data are described well by a relatively minimal model with three free parameters, yielding χ2red≃ 6.71/(9−3)=1.12. In contrast, the corresponding description of the J/ψ decays is insufficient (χ2_red≃ 132/(11−3)=16.5) and requires additional SU(3) flavor breaking and electromagnetic contributions for a fair agreement with data: χ2red≃ 9.87/(11−6)= 1.97. In the past, a small mixing of J/ψ with an invisible vector glueball was considered as a way to describe the decay patterns. However, we will show that our extended fits are `de facto' equivalent to those where a vector glueball mixes with the J/ψ, so that we cannot distinguish whether or not the vector glueball is present. Our results suggest that an important part of the ρπ puzzle may arise from additional contributions to the J/ψ→ VP amplitudes rather than from a suppression mechanism specific to the ψ(2S).
Related
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BibTeX
@misc{vereijken2026failure,
title = {{On the failure of the $12\%$ rule in $J/ψ$ and $ψ(2S)$ decays}},
author = {Arthur Vereijken and Francesco Giacosa},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.24961},
eprint = {2609.24961},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.24961},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - On the failure of the 12% rule in J/ψ and ψ(2S) decays
AU - Arthur Vereijken
AU - Francesco Giacosa
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.24961
UR - https://arxiv.org/abs/2609.24961
AB - The 12% rule relates hadronic decays of the J/ψ and ψ(2S) through the ratio of their wave functions at the origin, but is strongly violated in several vector--pseudoscalar (VP) channels, most prominently in the ρπ one. We study these decays within an effective chiral framework including strong and electromagnetic interactions, with the latter implemented through vector meson dominance. The ψ(2S)→ VP data are described well by a relatively minimal model with three free parameters, yielding χ^2_red≃ 6.71/(9−3)=1.12. In contrast, the corresponding description of the J/ψ decays is insufficient (χ^2_red≃ 132/(11−3)=16.5) and requires additional SU(3) flavor breaking and electromagnetic contributions for a fair agreement with data: χ^2_red≃ 9.87/(11−6)= 1.97. In the past, a small mixing of J/ψ with an invisible vector glueball was considered as a way to describe the decay patterns. However, we will show that our extended fits are `de facto' equivalent to those where a vector glueball mixes with the J/ψ, so that we cannot distinguish whether or not the vector glueball is present. Our results suggest that an important part of the ρπ puzzle may arise from additional contributions to the J/ψ→ VP amplitudes rather than from a suppression mechanism specific to the ψ(2S).
ER -