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Register a new userThe radiative decay of $psi(3770)$ into the predicted scalar state X(3700)
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We calculate the radiative decay width of the $psi(3770)$ into the dynamically generated scalar resonance X(3700) which is predicted in a previous paper. The results show that it is possible that the upgraded BEPC-II facility will generate enough statistics in order to observe this decay and thus confirm the existence of the X(3700).
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We present the formalism for the decay of dynamically generated scalar mesons with open- or hidden-charm and give results for the decay of D^*_{s0} (2317) to gamma D_s^* plus that of a hidden charm scalar meson state predicted by the theory around 3700 MeV decaying into gamma J/psi.
Motivated by a recent successful dynamical explanation for the newly observed fully-charm structure $X(6900)$ in the mass spectrum of di-$J/psi$ by LHCb [J.~Z.~Wang textit{et al.} arXiv:2008.07430], in this work, we extend the same dynamical rescattering mechanism to predict the line shape of more potential fully-heavy structures in the invariant mass spectrum of $J/psi psi(3686)$, $J/psi psi(3770)$, $psi(3686) psi(3686)$, and $J/psi Upsilon(1S)$ at high energy proton-proton collisions, whose verification in experiments should be helpful to further clarify the nature of $X(6900)$. The above final states of vector heavy quarkonia can be experimentally reconstructed more effectively by a $mu^+mu^-$ pair in the muon detector compared with $Qbar{Q}$ meson with other quantum numbers. Furthermore, the corresponding peak mass positions of each of predicted fully-heavy structures are also given. Our theoretical studies here could provide some valuable information for the future measurement proposals of LHCb and CMS, especially based on the accumulated data after completing Run III of LHC in the near future.
By using a 2.92 fb$^{-1}$ data sample taken at $sqrt{s} = 3.773$ GeV with the BESIII detector operating at the BEPCII collider, we search for the radiative transitions $psi(3770)togammaeta_c$ and $gammaeta_c(2S)$ through the hadronic decays $eta_c(eta_c(2S))to K^0_SK^pmpi^mp$. No significant excess of signal events above background is observed. We set upper limits at a 90% confidence level for the product branching fractions to be $mathcal{B}(psi(3770)togammaeta_c)times mathcal{B}(eta_cto K^0_SK^pmpi^mp) < 1.6times10^{-5}$ and $mathcal{B}(psi(3770)togammaeta_c(2S))times mathcal{B}(eta_c(2S)to K^0_SK^pmpi^mp) < 5.6times10^{-6}$. Combining our result with world-average values of $mathcal{B}(eta_c(eta_c(2S))to K^0_SK^pmpi^mp)$, we find the branching fractions $mathcal{B}(psi(3770)togammaeta_c) < 6.8times10^{-4}$ and $mathcal{B}(psi(3770)togammaeta_c(2S)) < 2.0times10^{-3}$ at a 90% confidence level.
The recently discovered fully charmed tetraquark candidate $X(6900)$ is analyzed within the frameworks of effective-range expansion, compositeness relation and width saturation, and a coupled multichannel dynamical study. By taking into account constraints from heavy-quark spin symmetry, the coupled-channel amplitude including the $J/psi J/psi,~ chi_{c0}chi_{c0}$ and $chi_{c1}chi_{c1}$ is constructed to fit the experimental di-$J/psi$ event distributions around the energy region near $6.9$ GeV. Another dynamical two-coupled-channel amplitude with the $J/psi J/psi$ and $psi(3770) J/psi$ is also considered to describe the same datasets. The three different theoretical approaches lead to similar conclusions that the two-meson components do not play dominant roles in the $X(6900)$. Our determinations of the resonance poles in the complex energy plane from the refined coupled-channel study are found to be consistent with the experimental analyses. The coupled-channel amplitudes also have another pole corresponding to a narrow resonance $X(6825)$ that we predict sitting below the $chi_{c0}chi_{c0}$ threshold and of molecular origin. We give predictions to the line shapes of the $chi_{c0}chi_{c0}$ and $chi_{c1}chi_{c1}$ channels, which could provide a useful guide for future experimental measurements.
In a recent measurement LHCb reported pronounced structures in the $J/psi J/psi$ spectrum. One of the various possible explanations of those is that they emerge from non-perturbative interactions of vector charmonia. It is thus important to understand whether it is possible to form a bound state of two charmonia interacting through the exchange of gluons, which hadronise into two pions at the longest distance. In this paper, we demonstrate that, given our current understanding of hadron-hadron interactions, the exchange of correlated light mesons (pions and kaons) is able to provide sizeable attraction to the di-$J/psi$ system, and it is possible for two $J/psi$ mesons to form a bound state. As a side result we find from an analysis of the data for the $psi(2S)to J/psi pipi$ transition including both $pipi$ and $Kbar K$ final state interactions an improved value for the $psi(2S)to J/psi$ transition chromo-electric polarisability: $|alpha_{psi(2S)J/psi}|= (1.8pm 0.1)~mbox{GeV}^{-3}$, where the uncertainty also includes the one induced by the final state interactions.
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