Properties of theΛ(1670)12−Resonance

Recently the Crystal Ball Collaboration measured precise new data for the near-threshold reaction $K^{-}p\to \eta \Lambda$, which is dominated by formation of the $\Lambda \left(1670\right){\frac{1}{2}}^{-}$. In this Letter, we present results of a unitary, multichannel analysis that incorporates the new Crystal Ball data. For our preferred fit, we obtain mass $M=1673\mathrm{}\pm 2\mathrm{MeV}$, width $\Gamma =23\mathrm{}\pm 6\mathrm{MeV}$, and elasticity $x=0.37\mathrm{}\pm 0.07$. This elasticity is significantly larger than previously recognized. Resonance parameters of our preferred fit are in striking agreement with the quark-model predictions of Koniuk and Isgur.