Study of nucleon and $Δ$ resonances from a systematic analysis of K^Σ photoproduction

A systematic analysis of the K^Σ photoproduction off proton is performed with all the available differential cross section data. We carry out a strategy different from the previous studies of these reactions, where, instead of fixing the parameters of the added resonances from PDG or pentaquark models, we add the resonance with a specific JP and leave its parameters to be determined from the experimental data. When adding only one resonance, the best result is to add one N(3/2⁻) resonance around $2097$ MeV, which substantially reduces the χ² per degree of freedom to $1.35$. There are two best solutions when adding two resonances, one is to add one N⁽3/2⁻) and one N⁽7/2⁻), the other is to add one N⁽3/2⁻) and one Δ⁽7/2⁻), leading the χ² per degree of freedom to be $1.10$ and $1.09$, respectively. The mass values of the N⁽3/2⁻) in the two resonance solutions are both near $2070$ MeV. Our solutions indicate that the N(3/2⁻) resonance around $2080$ MeV is strongly coupled with the K^Σ final state and support the molecular picture of N(2080, 3/2⁻).