Mass Splitting and Production of $Σ_c^0$ and $Σ_c^{++}$ Measured in $500 {GeV}$ $π^- -$N Interactions

Abstract

From a sample of $2722 \pm 78$ $Λ_c^+$ decaying to the $pK^-π^+$ final state, we have observed, in the hadroproduction experiment E791 at Fermilab, $143 \pm 20$ $Σ_c^0$ and $122 \pm 18$ $Σ_c^{++}$ through their decays to $Λ_c^+ π^{\pm}$. The mass difference $M(Σ_c^0) - M(Λ_c^+$) is measured to be $(167.38\pm 0.29\pm 0.15) {MeV}$; for $M(Σ_c^{++}) - M(Λ_c^+)$, we find $(167.76\pm 0.29\pm0.15) {MeV}$. The rate of $Λ_c^+$ production from decays of the $Σ_c$ triplet is $(22\pm 2\pm 3) {%}$ of the total $Λ_c^+$ production assuming equal rate of production from all three, as measured for $Σ_c^0$ and $Σ_c^{++}$. We do not observe a statistically significant $Σ_c$ baryon-antibaryon production asymmetry. The $x_F$ and $p_t^2$ spectra of $Λ_c^+$ from $Σ_c$ decays are observed to be similar to those for all $Λ_c^+$'s produced.