Electromagnetic probes revealing the inner structure of the $\Lambda_c(2940)$

Abstract

The $\Lambda_c(2940)$, an open-charm baryon discovered in 2006, has sparked interest due to its ``low mass puzzle'', paralleling the $X(3872)$ in the charmoniumlike sector. Both states challenge conventional hadronic interpretations, with the $X(3872)$ understood as a $D^*\bar{D}$ molecular state and the $\Lambda_c(2940)$ hypothesized as a $D^*N$ molecular state. This work investigates the radiative decay modes $\Lambda_c(2940) \to \Lambda_c(2286)\gamma$, $\Lambda_c(2940) \to \Lambda_c(2595)\gamma$, and $\Lambda_c(2940) \to \Lambda_c(2765)\gamma$, analogous to radiative transitions observed in the $X(3872)$. Using the one-boson-exchange model to obtain the $D^*N$ molecular spatial wave function as input, we calculate decay widths and their ratios, finding differences with different quantum number assumptions. Our findings underscore the potential of electromagnetic probes in revealing its nature and highlight the need for dedicated experimental studies to validate these theoretical predictions.