E-DECAYS TO ETA-PI-PI IN (P)OVER-BAR-P ANNIHILATION AT REST

We have observed the eta pi(+)pi(-) and eta pi(0) pi(0) decay modes of the E meson in ($) over bar pp annihilation at rest into pi(+)pi(-)pi(0) pi(0) eta. The mass and width of the E meson are 1409 +/- 3 and 86 +- 10 MeV. The production and decay branching ratio is B(($) over bar pp --> E pi pi)B(E --> eta pi pi = (3.3 +/- 1.0) x 10(-3). With a spin-parity analysis we determine that J(p) = 0(-). The observation of the eta pi(0) phi(0) decay mode establishes that E is isoscalar (C = + 1). We find that E decays to eta(pi pi)(s) (where (pi pi)(s) is an S-wave dipion) and pi alpha(0)(980)(--> pi eta) with a relative branching ratio of (78 +/- 16)%. Using the K ($) over bar K pi production and decay branching ratio measured earlier we determine that B[E --> $($) over bar$$ KK pi]/B[E --> eta pi pi] = 0.61 +/- 0.19. A comparison with observations in radiative J/psi decays suggests that E and iota/eta(1416) are identical.