Testing the hypothesis of vector X17 boson by D meson, Charmonium, and $\phi$ meson decays
The recent ATOMKI experiments provided evidence pointing towards the existence of an X17 boson in the anomalous nuclear transitions of Beryllium-8, Helium-4, and Carbon-12. In this work, we consider X17 boson contributions to the previously measured $D$ meson decays which include $D_s^{*+} \rightarrow D_s^+ e^+ e^-$, $D_s^{*+} \rightarrow D_s^+ \gamma$, $D^{*0} \rightarrow D^0 e^+ e^-$, and $D^{*0} \rightarrow D^0 \gamma$, as well as the measured decays of $\psi(2S) \rightarrow \eta_c e^+ e^-$, $\psi(2S) \rightarrow \eta_c \gamma$, $\phi \rightarrow \eta e^+ e^-$, and $\phi \rightarrow \eta \gamma$. Using the data of the above meson decays, we perform a fitting to the coupling parameters $\varepsilon_u, \varepsilon_c$, and $\varepsilon_s$ by treating the couplings $\varepsilon_u$ and $\varepsilon_c$ as independent from each other rather than assuming the generation universality $\varepsilon_u =\varepsilon_c$. It is found that the above fitting renders $|\varepsilon_c|=7.6\times 10^{-3}$, $|\varepsilon_s|=2.4\times 10^{-3}$ and a huge magnitude for $\varepsilon_u$, which is in serious tension with $\left|\varepsilon_u\right|$ determined from ATOMKI measurements. Using our fitted range for $\varepsilon_c$ and the range for $\varepsilon_d$ from ATOMKI measurements, we predict the range for $D^{*+} \rightarrow D^{+} e^+ e^-$ decay rate.