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

摘要: We report on a theoretical study of the π−p→D−D0p reaction near threshold within an effective Lagrangian approach. The production process is described by t channel D∗0 meson exchange, s-channel nucleon pole, and u channel Σ++c exchange. In our work, the final D0p results from the ground Λ+c(2286) state and also dominantly from the excited Λ+c(2940) state which is assumed as a D∗0p molecular state with spin parity JP=12+ or 12−. We calculate the total cross section of the π−p→D−D0p reaction. It is shown that the spin parity assignment of 12− for Λ+c(2940) gives a sizable enhancement for the total cross section in comparison with a choice of Jp=12+. 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 Λ+c(2940). It is expected that our model calculations can be tested by future experiments at J-PARC in Japan.