Eta and etaprime photoproduction on the nucleon with the isobar model EtaMAID2018

Abstract

The isobar model EtaMAID has been updated with new and high precision data for η and η photoproduction on protons and neutrons from MAMI, ELSA, GRAAL and CLAS. The background is described in a recently developed Regge-cut model, and for the resonance part the whole list of nucleon resonances has been investigated with 21 N * states contributing to η photoproduction and 12 N * states contributing to η photoproduction. A new approach is discussed to avoid double counting in the overlap region of Regge and resonances. A comparison is done among four newly updated partial waves analyses for observables and partial waves. Finally, the possibility of a narrow resonance near W = 1900 MeV is discussed, that would be able to explain unexpected energy and angular dependence of observables in p(γ, η )p near η threshold.

Decay patterns of low-lying Nss¯ states via strangeness channels

“…In addition, as we can see in Table III, N ss (1661) should couple strongly to ηN and KΛ channels, this is consistent with the large branching ratio of the N * (1535) resonance to ηN channel [31], and the strong coupling of N * (1535) to KΛ channel predicted by isobar model [16] and chiral perturbation theory [22]. One may notice that non-vanishing coupling constant of N * (1650) to KΣ channel was reported in a very recent work [45], while as we can see in Ref. [25], strong coupling between N * (1650) and…”

Photoproductions of f1(1285) and η′Yu1, Kong2 2020Phys. Rev. D2030View full textAdd to dashboardCite

“…The f 1 photoproduction will then be described with the trajectories of ρ 0 þ ω Regge poles and their VNN coupling constants the same as in the case of η and η 0 . The reliability of model prediction is confirmed by the roles of ρ 0 þ ω Regge poles in the η and η 0 cases, which were rather well established in previous studies [17,18]. In the model study of f 1 photoproduction, the ρ 0 exchange plays the leading role over the ω.…”

Recent results from the CBELSA/TAPS experiment at ELSA

“…A comparison of the multipoles shows that the new polarization data helps to reach the goal of Figure 8. The double polarization observable G is shown for the pη final state (black points) together with different PWA solutions (latest fit of BnGa (black line) [40], BnGa2011-02 (red line) [42], ηMAID2018 (green line) [48], SAID-GE09 (dark blue dotted) [49], JüBo-2015 (light blue dashed line) [50] and JüBo-2015-3 (light blue solid line) [51]). Taken from [14].…”