Coupled K+Λ and K0Λ photo

Abstract

The new γn → K 0 Λ data obtained from the CLAS and MAMI collaborations are analyzed by employing an effective Lagrangian method. The constructed model can describe all available experimental data in both γp → K + Λ and γn → K 0 Λ channels, simultaneously. The background part of the model is built from the appropriate intermediate states involving the nucleon, kaon, and hyperon exchanges, whereas the resonance part is constructed from the consistent interaction Lagrangians and propagators. To check the performance of the model a detailed comparison between the calculated observables and experimental data in both isospin channels is presented, from which a nice agreement can be observed. The discrepancy between the CLAS and MAMI data in the γn → K 0 Λ channel is analyzed by utilizing three different models; M1, M2, and M3 that fit the CLAS, MAMI, and both CLAS and MAMI data sets, respectively. The effect of this discrepancy is studied by investigating the significance of individual nucleon resonances and the predicted beamtarget helicity asymmetry E that has been measured by the CLAS collaboration recently. It is found that the N (1720)P13, N (1900)P13, and N (2060)D15 resonances are significant for improving the agreement between model calculation and data. This result is relatively stable to the choice of the model. The helicity asymmetry E can be better explained by the models M1 and M3. Finally, the effect of the N (1680)P11 narrow resonance on the cross section of both isospin channels is explored. It is found that the effect is more sensitive in the γn → K 0 Λ channel. In this case the model M3, that fits both CLAS and MAMI data, yields a more realistic effect.

Exotic Properties of N*(1895) and Its Impact on Photoproduction of Light Hyperons

“…Indeed nucleon resonances around 1890 MeV are not well understood, since most of the information in this energy region is extracted from the data on reactions producing KΛ and KΣ final states and different N * 's couple with a similar strength to these channels. For example, different descriptions have been brought forward for the peak present around 1900 MeV in the γp → K + Λ total cross sections [48][49][50][51][52]. Furthermore, different quark models [53][54][55][56] predict a different mass for the third S 11 state, with the values lying near 2 GeV.…”

The decay of N∗ (1895) to light hyperon resonances

“…[3]. Later partial wave investigations [4][5][6], however, concluded that the peak corresponds to the presence of a 3/2 + N * (1900) state. An alternative description for the same peak in the data is provided in Ref.…”