Pion Correlations and Resonance Effects in p‾p\overline{p}p Annihilation at Rest

We study pi pi correlations in the exclusive reactions pbarp -> 2 pi sup + 2 pi sup - and pbarp -> 2 pi sup + 2 pi sup -pi sup 0 at rest with complete reconstruction of the kinematics for each event. A new analysis technique has been developed which is model independent. With this new technique, which relies on double-differential distributions, no reference sample is needed to extract the correlation signal. The correlations are studied as a function of the four-pion invariant mass

Direct determination of two-pion correlations for p‾p→2π+2π−\overline{p}p \to 2\pi^{+}2\pi^{-} annihilation at rest

We study $\pi\pi$ correlations in the exclusive reaction \ppb \to 2\pi^+2\pi^- at rest measured by the CPLEAR experiment. Avoiding the introduction of an arbitrary reference sample, we analyse differential distributions for equal charge pion pairs removing the phase-space factor event by event. A peak at small relative momenta is most pronounced for large total momentum of the pair. The physical implications of bosonic symmetrization for the properties of the pion source, in particular its radius, are briefly discussed. The two extremes considered are the chaotic Hanbury-Brown--Twiss mechanism and the coherent Skyrmion model