Update on Partial-Wave Analysis

Abstract

Partial-wave analysis is one step in a process connecting experimental measurements to the N * states we are studying. Progress has been made in the area of 'model-independent' analysis. However, more model-dependent approaches are needed to cover broader energy ranges. An example of the problems faced by these more ambitious analyses is given.

Light Baryon Spectroscopy

“…Further details are given in the cited references. The symbols indicate which PWA (circle: BnGa-2019 [200], diamond: JüBo-2017 [201] and star: SAID [4,270]) use the data in their fits.…”

“…Further details are given in the cited references. The symbols indicate which PWA (circle: BnGa-2019 [200], diamond: JüBo-2017 [201] and star: SAID [270]) use the data in their fits. These processes make the multi-meson final states interesting for the partial wave analyses.…”

“…The Scattering Analysis Interactive Dial-in [439,161,440,441,197], or SAID, provided by the George Washington University (GWU) is one of the earliest ED analyses whose results were published on the internet [270]. In the most recent fits, the SAID-group employs phenomenological K-matrix type approaches for the analysis of pion-and photon-induced reactions [440,441].…”

“…The energy-dependence of the K-Matrix elements in the SAIDformalism is defined purely in terms of phenomenological polynomials. The only resonance which is put in as a genuine K-Matrix pole is the ∆(1232) 3 Different partial wave analyses of SAID are available for the comparison with photoproduction data at the SAID website [270]: the recent SAID-MA19 solution [178] for all pion reactions (γp → π 0 p, γp → π + n, γn → π − p, giving for the first time γn couplings for selected resonances and γn → π 0 n) as well as independent solutions for the pη [4], pη , KΛ and KΣ final states. It has to be mentioned here that the pη-and pη final states have been analyzed using methods other than the above-described Chew-Mandelstam K-matrix.…”

“…6) expanded their own respective database bit by bit over the years, which they use to extract the resonance parameters through fits to the measured observables. It is marked in which data sets are included in the latest BnGa [200], JüBo [201] and SAID [178,270] solutions, respectively.…”