Proton-antiproton annihilation and meson spectroscopy with the Crystal Barrel

Abstract

This report reviews the achievements of the Crystal Barrel experiment at the Low Energy Antiproton Ring (LEAR) at CERN. During seven years of operation Crystal Barrel has collected very large statistical samples in pp annihilation, especially at rest and with emphasis on final states with high neutral multiplicity. The measured rates for annihilation into various two-body channels and for electromagnetic processes have been used to test simple models for the annihilation mechanism based on the quark internal structure of hadrons. From three-body annihilations three scalar mesons, a 0 (1450), f 0 (1370) and f 0 (1500) have been established in various decay modes. One of them, f 0 (1500), may be identified with the expected ground state scalar glueball.

Geant4—a simulation toolkit

“…11. Comparison of the branchings in two particle final states in proton anti-proton annihilation [100] with the predictions of CHIPS.…”

Enhanced binding and cold compression of nuclei due to admixture of antibaryons

“…As is well known, the two-pion final states contribute only about 0.4% of the annihilation cross section. Even in vacuum all above mentioned channels contribute to σ A not more than 15% [22]. Therefore, we expect that only multi-pion final states contribute significantly to antiproton annihilation in the SBN.…”

Energy Distributions from Three-Body Decaying Many-Body Resonances

“…The underlying dynamics in particle physics may be described as quark rearrangements. Similar decays occur in annihilation of a proton-antiproton pair from a Coulomb-like orbit into three mesons [2]. In molecular physics an example is decay of excited states of the H 3 molecule into three hydrogen atoms [3].…”