$X$ structures in $B^+\to J/\psi\phi K^+$ as one-loop and double-triangle threshold cusps
| Autor: | Nakamura, Satoshi X. |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Phys. Lett. B 834, 137486 (2022) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1016/j.physletb.2022.137486 |
| Popis: | The LHCb data on $B^+\to J/\psi\phi K^+$ show four peaks and three dips in the $J/\psi\phi$ invariant mass distribution, and the peaks are interpreted as $X(4140)$, $X(4274)$, $X(4500)$ and $X(4685)/X(4700)$ resonance contributions. Interestingly, all the peaks and dips are located at (or close to) $D^*_{s}\bar{D}^{(*)}_{s}$, $D_{s0}^*(2317)\bar{D}^{(*)}_{s}$, $D_{s1}(2536)\bar{D}^{(*)}_{s}$, and $\psi'\phi$ thresholds. These coincidences suggest a close connection between the structures and the thresholds, which however has not been seriously considered in previous theoretical studies on the $X$ structures. In fact, if we utilize this connection and interpret the $X$ structures as common $s$-wave threshold cusps, we face a difficulty: $X(4274)$ and $X(4500)$ have spin-parity that conflict with the experimentally determined ones. In this work, we introduce double triangle mechanisms that cause threshold cusps significantly sharper than the ordinary one-loop ones of the same spin-parity. We demonstrate that all the $X$ and dip structures are well described by a combination of one-loop and double-triangle threshold cusps, thereby proposing a novel interpretation of the $X$ and dip structures. Comment: 12 pages, 6 figures; (v2) title changed; calculations corrected and all figures updated; 1 figure added; (v3) published version, fitting parameter values corrected |
| Databáze: | arXiv |
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