Correlation of pp data with predictions of improved six-quark structure models.

Abstract

Recent experimental data indicate a structure in \ensuremath{\Delta}${\ensuremath{\sigma}}_{L}$ corresponding to a pp mass of 2.7 GeV/${c}^{2}$, as earlier predicted for a six-quark $^{1}\mathrm{S}_{0}$ state by an R-matrix treatment of the cloudy-bag-model quark degrees of freedom interior to a coupled-isobar-channel system. The $^{1}\mathrm{S}_{0}$ model is improved to agree with 2\ensuremath{\pi} production data at 800 MeV laboratory energy. The resulting $^{1}\mathrm{S}_{0}$ partial wave and recently improved models of the background partial waves as well as older versions of the phase parameters predict experimental observables in the resonance region. The predicted width and inelasticity are consistent with the data. Detailed energy and angular dependence of the model are in agreement with \ensuremath{\Delta}${\ensuremath{\sigma}}_{L}$, ${C}_{\mathrm{LL}}$, and ${C}_{\mathrm{NN}}$ data in the resonance energy region. More data on these observables are needed to confirm the structure and its characteristics. Measurable aspects of the structure in other observables are displayed. Another six-quark resonance structure, in the $^{1}\mathrm{D}_{2}$ state, is described.