$G$-parity violating amplitudes in the $J/ψ\to π^+ π^-$ decay
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arXiv
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| Autori principali: | , , |
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| Natura: | Preprint |
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2016
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| _version_ | 1866915652043800576 |
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| author | Ferroli, Rinaldo Baldini Mangoni, Alessio Pacetti, Simone |
| author_facet | Ferroli, Rinaldo Baldini Mangoni, Alessio Pacetti, Simone |
| contents | The decays of the negative $G$-parity meson $J/ψ$ into even numbers of pions violate $G$-parity. Such decays, as well as other $G$-parity decays into hadrons, can be parametrized in terms of three main intermediate virtual states: one photon, one photon plus two gluons, and three gluons. Since the electromagnetic interaction does not conserve $G$-parity, $J/ψ$ decays into positive $G$-parity final states should be dominantly electromagnetic. Nevertheless, the one-photon contribution to $J/ψ\to π^+ π^-$, that can be estimated by exploiting the cross section $σ(e^+e^-\to π^+ π^-)$, differs from the observed decay probability for {more than} 4.5 standard deviations. We present a computation of the $ggγ$ amplitude based on a phenomenological description of the decay mechanism in terms of dominant intermediate states $ηγ$, $η'γ$ and $f_1(1285)γ$. The obtained value is of the order of the electromagnetic contribution. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_1611_04437 |
| institution | arXiv |
| publishDate | 2016 |
| record_format | arxiv |
| spellingShingle | $G$-parity violating amplitudes in the $J/ψ\to π^+ π^-$ decay Ferroli, Rinaldo Baldini Mangoni, Alessio Pacetti, Simone High Energy Physics - Phenomenology 81V35 The decays of the negative $G$-parity meson $J/ψ$ into even numbers of pions violate $G$-parity. Such decays, as well as other $G$-parity decays into hadrons, can be parametrized in terms of three main intermediate virtual states: one photon, one photon plus two gluons, and three gluons. Since the electromagnetic interaction does not conserve $G$-parity, $J/ψ$ decays into positive $G$-parity final states should be dominantly electromagnetic. Nevertheless, the one-photon contribution to $J/ψ\to π^+ π^-$, that can be estimated by exploiting the cross section $σ(e^+e^-\to π^+ π^-)$, differs from the observed decay probability for {more than} 4.5 standard deviations. We present a computation of the $ggγ$ amplitude based on a phenomenological description of the decay mechanism in terms of dominant intermediate states $ηγ$, $η'γ$ and $f_1(1285)γ$. The obtained value is of the order of the electromagnetic contribution. |
| title | $G$-parity violating amplitudes in the $J/ψ\to π^+ π^-$ decay |
| topic | High Energy Physics - Phenomenology 81V35 |
| url | https://arxiv.org/abs/1611.04437 |