Observation of a New Scalar Meson

Abstract

We have observed the production of a new scalar meson of mass 1255 ± 5 MeV and width 79 ± 10 MeV. The meson is observed primarily through the interference of the $S$-wave and $D$-wave ${K_s}^0{K_s}^0$ production amplitudes in the reaction ${\pi }^{-}p\to n{K_s}^0{K_s}^0$ at 6 and 7 GeV/c. The $S$-wave amplitude and phase are both observed to have Breit-Wigner behavior. The quantum numbers of the meson are $J^P=0^{+}$ and $C=+1\mathrm{}$ with $I^G=1^{-}$ preferred.