Partial wave analysis of $\bar pp \to \bar \Lambda \Lambda$

Abstract.

A partial wave analysis of PS185 data for $\bar pp \to \bar \Lambda \Lambda$ is presented. A ³ S ₁ cusp is identified in the inverse process $\bar \Lambda \Lambda \to \bar p p$ at threshold, using detailed balance to deduce cross sections from $\bar pp \to \bar \Lambda \Lambda$. Partial wave amplitudes for $\bar pp$ ³ P ₀, ³ F ₃, ³ D ₃ and ³ G ₃ exhibit a behaviour very similar to resonances observed in Crystal Barrel data. With this identification, the $\bar pp \to \bar \Lambda \Lambda$ data then provide evidence for a new I = 0, J ^PC = 1^- resonance with mass $M = 2290 \pm 20$ MeV, $\Gamma = 275 \pm 35$ MeV, coupling to both ³ S ₁ and ³ D ₁.