Dynamical selection rules from $p \bar p$ annihilation at restin three meson final states

Abstract.

The hadronic annihilation branching-ratios in quasi-two-body final states have been obtained from the observation of the reactions $\bar p p$ $\rightarrow$ $\pi^ + \pi^- \pi^0$, $K^ + K^- \pi^0,K^\pm \pi^\mp K^0$ at rest in hydrogen targets at different densities. The enhancement or suppression of specific hadronic channels connected to dynamical selection rules is observed in the production of different resonances both in protonium S and P-waves, systematically investigated for the first time. Besides the well known $\rho(770) \pi$ and $a_2(1320) \pi$ enhancement from ³ S ₁ and ¹ S ₀ partial waves, the dominance of one isospin source in $K^*(892) \bar K$ production, well established from S-waves, is confirmed also in P-waves (¹ S ₀, I = 0; ³ S ₁, I = 1; ¹ P ₁, I = 0; ³ P ₁, I = 0; ³ P ₂, I = 1). In addition, the experimental data clearly show a strong suppression of $\phi(1020) \pi$ and $a_0(980) \pi$ final states from P-wave which has a remarkable coincidence with $K^*(892) \bar K$ pattern production.