The Role of a1(1260) in π-p → a1- (1260)p and π-p → π-ρ0p Reactions Near Threshold

We report on a theoretical study of the pi(-)p -> a(1)(-) (1260)p and pi(-)p -> pi(-)rho(0)p reactions near threshold within an effective Lagrangian approach. The production process is described by t-channel rho(0) meson exchange. For the pi(-)p -> pi(-)rho(0)p reaction, the final pi(-)rho(0) results from the decay of the a(1) (1260) resonance, which is assumed as a dynamically generated state from the K*(K) over bar and per coupled channel interactions. We calculate the total cross section of the pi(-)p -> a(1)(-) (1260)p reaction. It is shown that, with the coupling constant of the a(1) (1260) to per channel obtained from the chiral unitary theory and a cut off parameter Lambda(rho) similar to 1.5 GeV in the form factors, the experimental measurement can be reproduced. Furthermore, the total and differential cross sections of pi(-)p -> a(1)(-) (1260)p -> pi(-)rho(0)p reaction are evaluated, and it is expected that our model calculations can be tested by future experiments. These reactions are important for the study of the al (1260) resonance and would provide further constraints on the properties of the a(1) (1260) state.