$J/\psi$ absorption by nucleons in the meson-exchange model

We reinvestigate the $J/\psi$ dissociation processes induced by the reactions with nucleons, $J/\psi +N\to {\overline{D}}^{(*)}+{\Lambda }_c$, in the meson-exchange model. Main constraints used in this work are vector-meson dominance and charm vector-current conservation. We show that the cross section for $J/\psi +N\to \overline{D}+{\Lambda }_c$ can be larger than that for $J/\psi +N\to {\overline{D}}^{*}+{\Lambda }_c$ when these constraints are imposed. The dependence of the cross sections on the coupling constants is analyzed in detail, and the comparison with the recent quark-interchange model predictions is also made.

Figure 1

Diagrams for the reaction of $J/\psi +N\to {\overline{D}}^{(*)}+{\Lambda }_c$.

Figure 2

Total cross section for (a) $J/\psi +p\to {\overline{D}}^0+{\Lambda }_c$ and (b) $J/\psi +p\to {\overline{D}}^{*0}+{\Lambda }_c$ when the tensor interactions are turned off, ${\kappa }_{\psi {\Lambda }_c{\Lambda }_c}={\kappa }_{D^{*}N{\Lambda }_c}=0$. The dashed, dotted, and dot-dashed lines are the contributions from the $t$-channel, $u$-channel, and anomalous terms, respectively, and the solid lines are their sums.

Figure 3

Total cross section for (a) $J/\psi +p\to {\overline{D}}^0+{\Lambda }_c$ and (b) $J/\psi +p\to {\overline{D}}^{*0}+{\Lambda }_c$ with ${\kappa }_{\psi {\Lambda }_c{\Lambda }_c}=-0.94$ and ${\kappa }_{D^{*}N{\Lambda }_c}=0$. Notations are the same as in Fig. 2.

Figure 4

Total cross section for (a) $J/\psi +p\to {\overline{D}}^0+{\Lambda }_c$ and (b) $J/\psi +p\to {\overline{D}}^{*0}+{\Lambda }_c$ with ${\kappa }_{\psi {\Lambda }_c{\Lambda }_c}=-0.94$ and ${\kappa }_{D^{*}N{\Lambda }_c}=2.65$. In (a), the $u$-channel diagram dominates and the contributions from the other diagrams are suppressed and cannot be seen. In (b), the dot-dash-dashed line is the contribution from the contact term. Other notations are the same as in Fig. 2.