Role of the ${\Lambda }_c^{+}(2940)$ in the ${\pi }^{-}p\to D^{-}{D}^{0}p$ reaction close to threshold

Abstract

We report on a theoretical study of the ${\pi }^{-}p\to D^{-}{D}^{0}p$ reaction near threshold within an effective Lagrangian approach. The production process is described by $t$ channel $D^{\ast 0}$ meson exchange, $s$-channel nucleon pole, and $u$ channel ${\Sigma }_c^{++}$ exchange. In our work, the final $D^{0}p$ results from the ground ${\Lambda }_c^{+}(2286)$ state and also dominantly from the excited ${\Lambda }_c^{+}(2940)$ state which is assumed as a $D^{\ast 0}p$ molecular state with spin parity $J^P={\frac{1}{2}}^{+}$ or ${\frac{1}{2}}^{-}$. We calculate the total cross section of the ${\pi }^{-}p\to D^{-}{D}^{0}p$ reaction. It is shown that the spin parity assignment of ${\frac{1}{2}}^{-}$ for ${\Lambda }_c^{+}(2940)$ gives a sizable enhancement for the total cross section in comparison with a choice of $J^p={\frac{1}{2}}^{+}$. However, our theoretical result of the total cross section is sensitive to the value of the cutoff parameter involved in the form factor of the exchanged off-shell particles. Moreover, we also calculate the second order differential cross section and find it can be used to determine the parity of the ${\Lambda }_c^{+}(2940)$. It is expected that our model calculations can be tested by future experiments at J-PARC in Japan.

Comments: Published version. Phys. Rev. D 92, 034029 (2015)