The evidence for a pentaquark signal and kinematic reflections

Abstract

Several recent experiments have reported evidence for a narrow baryon resonance with positive strangeness $({\ensuremath{\Theta}}^{+})$ at a mass of $1.54\mathrm{GeV}{/c}^{2}.$ Baryons with $S=+1$ cannot be conventional qqq states and the reports have thus generated much theoretical speculation about the nature of possible $S=+1$ baryons, including a 5-quark, or pentaquark, interpretation. We show that narrow enhancements in the ${K}^{+}n$ effective mass spectrum can be generated as kinematic reflections resulting from the decay of mesons, such as the ${f}_{2}(1275),$ the ${a}_{2}(1320)$ and the ${\ensuremath{\rho}}_{3}(1690).$