2017/05/31 by Tobias Isken, Bastian Kubis, Sebastian P. Schneider +1 · 45 citations
Physics and Astronomy · #Amplitude #Dispersion (optics) #Dispersion relation #High-Energy Particle Collisions Research #Isospin #Particle physics theoretical and experimental studies #Perturbation (astronomy) #Phase (matter) #Quantum Chromodynamics and Particle Interactions #Representation (politics) #Scattering #hep-ex #hep-ph #nucl-ex #nucl-th
paper · pdf · doi:10.1140/epjc/s10052-017-5024-1
published in The European Physical Journal C 77(7) (Springer Science+Business Media) · 22 pages, 10 figures; v2: added footnote, version published in EPJC
openalex created_date 2017/05/26 · openalex publication_date 2017/07/01 · arxiv created 2017/07/24 · arxiv updated 2017/07/25 · openalex updated_date 2026/08/06
We present a dispersive analysis of the decay amplitude for η '→ η π π that is based on the fundamental principles of analyticity and unitarity. In this framework, final-state interactions are fully taken into account. Our dispersive representation relies only on input for the π π and π η scattering phase shifts. Isospin symmetry allows us to describe both the charged and neutral decay channel in terms of the same function. The dispersion relation contains subtraction constants that cannot be fixed by unitarity. We determine these parameters by a fit to Dalitz-plot data from the VES and BES-III experiments. We study the prediction of a low-energy theorem and compare the dispersive fit to variants of chiral perturbation theory.