engleski

Meson production on complex nuclei by Pi- with Crystal Ball detector

We report on preliminary results for the production of neutral mesons by 750 MeV/c pi^- on complex nuclear targets (C, Al, Cu) and hydrogen. Our simultaneous measurement of pi^0, 2pi^0, and eta final states allows an investigation of the nuclear final-state-interaction effects. The data show that nuclear absorption is mainly responsible for an observed change in the shape of the 2 pi^0 invariant mass spectra. Our preliminary result for the sigma to gamma gamma branching ratio is BR(sigma to gamma gamma) < 3.6 x 10^-3 x phi at 90% C.L. on a carbon target, where phi is the fraction of 2 pi^0 produced via the sigma intermediate state.

pi- p; inclusive reaction; pi- nucleus; inclusive reaction

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