Exclusive production of p anti pπ+π- in photon photon collisions

A measurement of the e+e- → e+e-p anti pπ+π- process with the TPC/Two-Gamma facility at the PEP e+e- storage ring at SLAC is reported. Forty-five p anti pπ+π- events were identified in data corresponding to an integrated e+e- luminosity of 142 pb-1. The cross section for γγ→ p anti pπ+π- is given both as a function of Wγγ, the γγ center-of-mass energy, with Wγγ between 2.5 and 5.5 GeV, and as a function of the invariant mass squared, q2, of one of the photons, with -q2 < 7 GeV2. This cross section falls much less rapidly with Wγγ than does the cross section for a similar process, γγ → p anti p. No Δ0 anti Δ0 production is observed, and only a small fraction of the events at low Wγγ is consistent with γγ → Δ++ anti Δ--, Δ++ anti pπ- or anti Δ--pπ+. In an expanded search through the same data, four events compatible with either Λ anti Λ (Λ → pπ-) or Σ0 anti Λ(Σ0 → Λγ) production were found. (author). 14 refs.; 5 figs.; 1 tab