We have measured the quadratic slope parameter a for η → 3π0 decay. Our final result is α = -0.031(4). We have also obtained the branching ratio (BR) for the double radiative decay η → π0 γγ. Our preliminary result is BR(η → π0) = 3.2(9) × 10-4. These new measurements were performed using the recent (1998) high-statistics sample of 1.9 × 107 η produced at the AGS at BNL in π-p → nη close to threshold. The η decay into neutrals was detected with the Crystal Ball multiphoton spectrometer. Both measurements provide important tests of chiral perturbation theory (χPTh). Our result for a is four times more precise than the present world data and disagrees with current χPTh calculations by about four standard deviations. Our branching ratio for η → π0γγ is about half the current value and is in agreement with the χPTh predictions.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Nuclear and High Energy Physics