Criterion for the Existence of the $G(3900)$ Resonance
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866918139693891584 |
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| author | Huang, Yin Chen, Xurong |
| author_facet | Huang, Yin Chen, Xurong |
| contents | About 18 years ago, the BABAR and the Belle Collaborations reported evidence for a new $c\bar{c}$ structure near $3900~\mathrm{MeV}$ in $e^{+}e^{-} \to D\bar{D}$, triggering debate over whether it represents a genuine hadronic state or arises from interference effects and the opening of the $D^{*}\bar{D}$ threshold. The issue remained unsettled until 2024, when BESIII, with an enlarged $e^{+}e^{-} \to D\bar{D}$ sample, confirmed the presence of the $G(3900)$ structure, reviving discussion of its nature. Although it has been proposed as a $P$-wave $D\bar{D}^{*}$ molecular state, no consensus has emerged, and interference effects remain a plausible explanation. In this Letter, we show that analyzing the $e^{+}e^{-}\to D\bar{D}$ cross section as a function of the transverse momentum of the final-state $D$ meson reveals a prominent Jacobian peak. This feature cannot be generated by interference effects alone and thus provides direct evidence for the existence of $G(3900)$. Moreover, the peak position is highly sensitive to the actual mass of $G(3900)$, offering a precise determination method. Our results further disfavor the interpretation of $G(3900)$ as a $D\bar{D}^{*}$ molecular state, pointing instead to alternative internal structures. The criterion illustrated by $G(3900)$ can be extended to other hadronic systems, offering a powerful tool to identify genuine resonances. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_06353 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Criterion for the Existence of the $G(3900)$ Resonance Huang, Yin Chen, Xurong High Energy Physics - Phenomenology High Energy Physics - Experiment About 18 years ago, the BABAR and the Belle Collaborations reported evidence for a new $c\bar{c}$ structure near $3900~\mathrm{MeV}$ in $e^{+}e^{-} \to D\bar{D}$, triggering debate over whether it represents a genuine hadronic state or arises from interference effects and the opening of the $D^{*}\bar{D}$ threshold. The issue remained unsettled until 2024, when BESIII, with an enlarged $e^{+}e^{-} \to D\bar{D}$ sample, confirmed the presence of the $G(3900)$ structure, reviving discussion of its nature. Although it has been proposed as a $P$-wave $D\bar{D}^{*}$ molecular state, no consensus has emerged, and interference effects remain a plausible explanation. In this Letter, we show that analyzing the $e^{+}e^{-}\to D\bar{D}$ cross section as a function of the transverse momentum of the final-state $D$ meson reveals a prominent Jacobian peak. This feature cannot be generated by interference effects alone and thus provides direct evidence for the existence of $G(3900)$. Moreover, the peak position is highly sensitive to the actual mass of $G(3900)$, offering a precise determination method. Our results further disfavor the interpretation of $G(3900)$ as a $D\bar{D}^{*}$ molecular state, pointing instead to alternative internal structures. The criterion illustrated by $G(3900)$ can be extended to other hadronic systems, offering a powerful tool to identify genuine resonances. |
| title | Criterion for the Existence of the $G(3900)$ Resonance |
| topic | High Energy Physics - Phenomenology High Energy Physics - Experiment |
| url | https://arxiv.org/abs/2509.06353 |