QCD sum rule analysis of local meson-meson currents for the $K(1690)$ state
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arXiv
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| Main Authors: | , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866911614620401664 |
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| author | Mu, Yi-Qi Xu, Peng-Wen Chen, Si-Tong Wei, Yi-Tong Zhang, Ge-Jia Wan, Bing-Dong |
| author_facet | Mu, Yi-Qi Xu, Peng-Wen Chen, Si-Tong Wei, Yi-Tong Zhang, Ge-Jia Wan, Bing-Dong |
| contents | The nature of the recently observed $K(1690)$ state, reported by the COMPASS Collaboration as a candidate for a strange crypto-exotic meson with $J^P=0^-$, remains unclear. In this work, we investigate whether it can be described by local meson-meson currents within the framework of QCD sum rules. We construct a set of local meson-meson-type interpolating currents with $J^P=0^-$, covering the representative Dirac structures $0^- \otimes 0^+$, $0^+ \otimes 0^-$, $1^- \otimes 1^+$, $1^+ \otimes 1^-$, as well as tensor configurations. For all these currents, we perform a systematic operator product expansion up to dimension-eight condensates and carry out a detailed analysis of Borel stability, continuum threshold dependence, and pole contributions. We find that the extracted masses are consistently located around $2~\mathrm{GeV}$ or higher, significantly above the experimental mass of the $K(1690)$. This behavior is highly stable against variations of QCD parameters and the choice of interpolating currents, and is observed universally across all the considered configurations. The absence of any low-lying pole compatible with the COMPASS signal therefore disfavors interpreting the $K(1690)$ as a state predominantly coupled to these local meson-meson currents within the QCD sum rule framework. Our results thus make a compact multiquark configuration a more plausible explanation for this state. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_20439 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | QCD sum rule analysis of local meson-meson currents for the $K(1690)$ state Mu, Yi-Qi Xu, Peng-Wen Chen, Si-Tong Wei, Yi-Tong Zhang, Ge-Jia Wan, Bing-Dong High Energy Physics - Phenomenology The nature of the recently observed $K(1690)$ state, reported by the COMPASS Collaboration as a candidate for a strange crypto-exotic meson with $J^P=0^-$, remains unclear. In this work, we investigate whether it can be described by local meson-meson currents within the framework of QCD sum rules. We construct a set of local meson-meson-type interpolating currents with $J^P=0^-$, covering the representative Dirac structures $0^- \otimes 0^+$, $0^+ \otimes 0^-$, $1^- \otimes 1^+$, $1^+ \otimes 1^-$, as well as tensor configurations. For all these currents, we perform a systematic operator product expansion up to dimension-eight condensates and carry out a detailed analysis of Borel stability, continuum threshold dependence, and pole contributions. We find that the extracted masses are consistently located around $2~\mathrm{GeV}$ or higher, significantly above the experimental mass of the $K(1690)$. This behavior is highly stable against variations of QCD parameters and the choice of interpolating currents, and is observed universally across all the considered configurations. The absence of any low-lying pole compatible with the COMPASS signal therefore disfavors interpreting the $K(1690)$ as a state predominantly coupled to these local meson-meson currents within the QCD sum rule framework. Our results thus make a compact multiquark configuration a more plausible explanation for this state. |
| title | QCD sum rule analysis of local meson-meson currents for the $K(1690)$ state |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2604.20439 |