Updated analysis of πNelastic scattering data to 2.1 GeV: The baryon spectrum

Abstract

We present the results of energy-dependent and single-energy partial-wave analyses of πN elastic scattering data with laboratory kinetic energies below 2.1 GeV. Resonance structures have been extracted using Breit-Wigner fits, speed plots, and a complex plane mapping of the associated poles and zeroes. This is the first set of resonance parameters from a VPI analysis constrained by fixed-t dispersion relations. We have searched our solutions for structures which may have been missed in our previous analyses, finding candidates in the S 11 and F 15 partial-wave amplitudes. Our results are compared with those found by the Karlsruhe, Carnegie-Mellon−Berkeley, and Kent State groups.

Time delay and time advance in resonance theory

“…Then the high energy behavior can be phenomenologically corrected by introducing appropriate form factors, which account also for the fact that the interacting particles are not pointlike. These corrections are widely applied in the phenomenological analysis [10,21,22,23].…”

Excitation of S11 resonances in pion scattering and pion photoproduction on the proton

“…Even though the existence of the four-star baryon resonances is certain, some very large discrepancies exist in their properties as obtained from different analyses. One example is the extracted width of the four-star S 11 (1535) state given as 66 MeV [2], 120 ± 20 MeV [3], 151 ± 27 MeV [4], 151 − 198 MeV [5], and 270 ± 50 MeV [6]. The differences between different analyses arise mostly from the data set included in the analysis or the separation of background and resonance contributions.…”

Inversion potentials for meson-nucleon and meson-meson interactions

“…Partial wave phase shifts of the πN system are determined by an analysis of elastic and charge exchange scattering π + p → π + p, π − p → π − p and π − p → π 0 n. They form a complete set of observables entering a partial wave analysis with isospin T = 1 2 and 3 2 [5]. The notation for the isospin and angular momentum channels is ℓ 2T,2S .…”

“…The notation for the isospin and angular momentum channels is ℓ 2T,2S . We used the SM95 analysis of Arndt et al for channels ℓ ≤ 3 [4,5].…”

“…for πN [5] and K + N [6], of Froggatt et al for ππ [7] and of Estabrooks et al for Kπ [8]. We limit ourselves to subinelastic and subreaction threshold data.…”