Decay chain information on the newly discovered double charm baryon state ${\mathrm{\Xi }}_{cc}^{++}$

We interpret the new double charm baryon state found by the LHCb Collaboration in the invariant mass distribution of the set of final state particles $({\mathrm{\Lambda }}_c^{+}{K}^{-}{\pi }^{+}{\pi }^{+})$ as being at the origin of the decay chain ${\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}(\to {\mathrm{\Lambda }}_c^{+}{\pi }^{+})+{\overline{K}}^{*0}(\to K^{-}{\pi }^{+})$. The nonleptonic decay ${\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}+{\overline{K}}^{*0}$ belongs to a class of decays where the quark flavor composition is such that the decay proceeds solely via the factorizing contribution precluding a contamination from internal $W$-exchange. We use the covariant confined quark model previously developed by us to calculate the four helicity amplitudes that describe the dynamics of the transition ${\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}$ induced by the effective $(c\to u)$ current. We then proceed to calculate the rate of the decay as well as the polarization of the ${\mathrm{\Sigma }}_c^{++}$ and ${\mathrm{\Lambda }}_c^{+}$ baryons and the longitudinal/transverse composition of the ${\overline{K}}^{*0}$. We estimate the decay ${\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}{\overline{K}}^{*0}$ to have a branching rate of $B({\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}{\overline{K}}^{*0})\sim 10.5\%$. As a byproduct of our investigation we have also analyzed the decay ${\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}{\overline{K}}^0$ for which we find a branching ratio of $B({\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}{\overline{K}}^0)\sim 2.5\%$.