Unquenched quark-model calculation of X(3872) electromagnetic decays

Abstract

A recent quark-model description of X(3872) as an unquenched $2{}^3{P}_1$ $c\bar{c}$ state is generalised by now including all relevant meson-meson configurations, in order to calculate the widths of the experimentally observed electromagnetic decays $X(3872)\to \gamma J/\psi$ and $X(3872)\to \gamma \psi (2S)$. Interestingly, the inclusion of additional two-meson channels, most importantly $D^{\pm }{D}^{\star \mp }$, leads to a sizeable increase of the $c\bar{c}$ probability in the total wave function, although the $D^0{\bar{D}}^{\star 0}$ component remains the dominant one. As for the electromagnetic decays, unquenching strongly reduces the $\gamma \psi (2S)$ decay rate yet even more sharply enhances the $\gamma J/\psi$ rate, resulting in a decay ratio compatible with one experimental observation but in slight disagreement with two others. Nevertheless, the results show a dramatic improvement as compared to a quenched calculation with the same confinement force and parameters. Concretely, we obtain $\Gamma (X(3872)\to \gamma \psi (2S))=28.9$ keV and $\Gamma (X(3872)\to \gamma J/\psi )=24.7$ keV, with branching ratio ${\mathcal{R}}_{\gamma \psi }=1.17$.

10 pages, 2 figures (3 plots), 10 tables, SVJOUR style; v2: typos corrected, 2 references added, remarks added on dipole approximation, version accepted for publication in Eur. Phys. J. C

References in corpus (8)

• Big-Bang Nucleosynthesis
• Estimate for the X(3872) to gamma J/psi decay width
• Radiative E1 decays of X(3872)
• Radiative decay of the X(3872) as a mixed molecule-charmonium state in QCD Sum Rules
• $X(3872)$, $X_b$, and the ${\chi }_{b1}(3P)$ state
• Coupling constants and transition potentials for hadronic decay modes of a meson
• Strong and radiative decays of X(3872) as a hadronic molecule with a negative parity
• M2 signatures in psi(2S) radiative decays

Cited by in corpus (9)

• Doubly-heavy tetraquarks
• Observation of multiplicity-dependent prompt ${\chi }_{c1}(3872)$ and $\psi (2S)$ production in $pp$ collisions
• $X(3872)$, $X_b$, and the ${\chi }_{b1}(3P)$ state
• Modern meson spectroscopy: the fundamental role of unitarity
• The role of electromagnetic interaction in the $X(3872)$ and its analogs
• Study of $e^{+}{e}^{-}\to \omega X(3872)$ and $\gamma X(3872)$ from 4.66 to 4.95 GeV
• Proper constituent gluon mass as the final piece to construct hybrid mesons
• Study of conventional and non-conventional scalar and vector mesons
• Electromagnetic probes revealing the inner structure of the ${\Lambda }_c(2940)$