The role of $a_1(1260)$ in $\pi^- p \to a^-_1(1260) p$ and $\pi^- p \to \pi^- \rho^0 p$ reactions near threshold

Understand

We report on a theoretical study of the $\pi^- p \to a^-_1(1260) p$ and $\pi^- p \to \pi^- \rho^0 p$ reactions near threshold within an effective Lagrangian approach.

• The production process is described by $t$-channel $\rho^0$ meson exchange.
• For the $\pi^- p \to \pi^- \rho^0 p$ 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 $K^* \bar K$ and $\rho \pi$ coupled channel interactions.
• We calculate the total cross section of the $\pi^- p \to a^-_1(1260) p$ reaction.