D(*)N interaction and the structure of Σc(2800) and Λc(2940) in chiral effective field theory

Abstract

We study the $DN$ and ${D}^{*}N$ interactions to probe the inner structure of ${\mathrm{\ensuremath{\Sigma}}}_{c}(2800)$ and ${\mathrm{\ensuremath{\Lambda}}}_{c}(2940)$ with the chiral effective field theory to the next-to-leading order. We consider the contact term, one-pion-exchange and two-pion-exchange contributions to characterize the short-, long-, and mid-range interactions of the ${D}^{(*)}N$ systems. The low energy constants of the ${D}^{(*)}N$ systems are related to those of the $N\overline{N}$ interaction with a quark level Lagrangian that was inspired by the resonance saturation model. The $\mathrm{\ensuremath{\Delta}}(1232)$ degree of freedom is also included in the loop diagrams. The attractive potential in the $[DN{]}_{J=1/2}^{I=1}$ channel is too weak to form a bound state, which indicates that the explanation of ${\mathrm{\ensuremath{\Sigma}}}_{c}(2800)$ as the compact charmed baryon is more reasonable. Meanwhile, the potentials of the isoscalar channels are deep enough to yield the molecular states. We obtain the masses of the $[DN{]}_{J=1/2}^{I=0}$, $[{D}^{*}N{]}_{J=1/2}^{I=0}$, and $[{D}^{*}N{]}_{J=3/2}^{I=0}$ systems to be 2792.0, 2943.6, and 2938.4 MeV, respectively. The ${\mathrm{\ensuremath{\Lambda}}}_{c}(2940)$ is probably the isoscalar ${D}^{*}N$ molecule considering its low mass puzzle. Besides, the ${\mathrm{\ensuremath{\Lambda}}}_{c}(2940)$ signal might contain the spin-$\frac{1}{2}$ and spin-$\frac{3}{2}$ two structures, which can qualitatively explain the significant decay ratio to ${D}^{0}p$ and ${\mathrm{\ensuremath{\Sigma}}}_{c}\ensuremath{\pi}$. We also study the ${\overline{B}}^{(*)}N$ systems and predict the possible molecular states in the isoscalar channels. We hope experimentalists could hunt for the open charmed molecular pentaquarks in the ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ final state.