Study of excited $$\varvec{\varXi }$$ baryons with the $$\overline{\text{ P }}$$ANDA detector

Abstract

The study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards $$N^*$$ N ∗ and $$\varDelta $$ Δ spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the $$N^*$$ N ∗ and $$\varDelta $$ Δ spectra. The future antiproton experiment $$\overline{\text{ P }}$$ P ¯ ANDA will provide direct access to final states containing a $${\overline{\varXi }}\varXi $$ Ξ ¯ Ξ pair, for which production cross sections up to $$\mu \text{ b }$$ μ b are expected in $$\bar{\text{ p }}$$ p ¯ p reactions. With a luminosity of $$L=10^{31}$$ L = 10 31 cm$$^{-2}$$ - 2 s$$^{-1}$$ - 1 in the first phase of the experiment, the expected cross sections correspond to a production rate of $$\sim 10^6\, \text{ events }/\text{day }$$ ∼ 10 6 events / day . With a nearly $$4\pi $$ 4 π detector acceptance, $$\overline{\text{ P }}$$ P ¯ ANDA will thus be a hyperon factory. In this study, reactions of the type $$\bar{\text{ p }}$$ p ¯ p $$\rightarrow $$ → $${\overline{\varXi }}^{+}$$ Ξ ¯ + $$\varXi ^{*-}$$ Ξ ∗ - as well as $$\bar{\text{ p }}$$ p ¯ p $$\rightarrow $$ → $${\overline{\varXi }}^{*+}$$ Ξ ¯ ∗ + $$\varXi ^{-}$$ Ξ - with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.