Invariant mass

Invariant mass of the (nK⁺) system obtained from CLAS using the reaction γ+d→pK^-(nK⁺). The sharp peak at the mass of 1.542 GeV/c² has the exotic quantum number S = +1. The fit to the peak and a smooth background gives a significance of 5.8 σ. The dotted histogram shows the spectrum associated with Λ(1520) production.

Back to article