0000000001164726
AUTHOR
Rolf Landua
The Atomic Cascade in p̄p and Implications for p̄p Annihilations at Rest
Many experiments at LEAR will study the pp interaction at rest via the formation of an atomic bound system of p and p (protonium). Protonium is formed in a highly excited state when the antiproton has been stopped in a target containing gaseous or liquid hydrogen and after it has been captured by a H2 molecule. The subsequent deexcitation process ends with the annihilation of the pp atom from an atomic s-, p- or d-state. The knowledge of the angular momentum of this atomic state is clearly of fundamental importance in the analysis of the annihilation final states. The aim of this contribution is to review the present experimental and theoretical understanding of the de-excitation and annihi…
Antiproton-proton annihilation at rest into two-body final states
We report measurements of branching ratios for production of a series of two meson final states in $$\bar p$$ p annihilations at rest in liquid hydrogen. We find: $$\begin{gathered} BR(\bar pp \to \pi ^ + \pi ^ - ) = (3.07 \pm 0.13) \cdot 10^{ - 3} \hfill \\ BR(\bar pp \to K^ + K^ - ) = (0.99 \pm 0.05) \cdot 10^{ - 3} \hfill \\ BR(\bar pp \to \pi ^0 \pi ^0 ) = (6.93 \pm 0.43) \cdot 10^{ - 4} \hfill \\ BR(\bar pp \to \pi ^0 \eta ) = (2.12 \pm 0.12) \cdot 10^{ - 4} \hfill \\ BR(\bar pp \to \pi ^0 \omega ) = (5.73 \pm 0.47) \cdot 10^{ - 3} \hfill \\ BR(\bar pp \to \pi ^0 \eta ') = (1.23 \pm 0.13) \cdot 10^{ - 4} \hfill \\ BR(\bar pp \to \eta \eta ) = (1.64 \pm 0.10) \cdot 10^{ - 4} \hfill \\ B…