2018/09/30 by E.C. Perotti, Elisabetta Perotti, Göran Fäldt +4 · 1 citation
Physics and Astronomy · #Annihilation #Baryon #Condensed matter physics #Hadron #Helicity #High-Energy Particle Collisions Research #Lambda #Omega #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Spins #hep-ex #hep-ph #nucl-ex
paper · pdf · doi:10.1103/physrevd.99.056008
published as Phys. Rev. D 99, 056008 (2019) · 16 pages;update: 1 figure, extended introduction and examples, results not changed
arxiv created 2019/02/28 · openalex publication_date 2019/03/18 · arxiv updated 2019/03/27 · openalex created_date 2019/06/27 · openalex updated_date 2026/08/05
Using the helicity formalism of Jacob and Wick, we derive spin density matrices of baryon antibaryon pairs produced in e+e^\ensuremath- annihilation. We consider the production of pairs with spins 1/2+1/2, 1/2+3/2 (+c.c.) and 3/2+3/2. We provide modular expressions to include chains of weak hadronic two-body decays of the produced hyperons. The expressions are suitable for the analysis of high statistics data from J/\ensuremathψ and \ensuremathψ(2S) decays at e+e^\ensuremath- colliders, by fits to the fully differential angular distributions of the measured particles. We illustrate the method by examples, such as the inclusive measurement of the e+e^\ensuremath-\ensuremath→\ensuremathψ(2S)\ensuremath→\mathrm\ensuremathΩ^\ensuremath-\mathrm\ensuremathΩ+ process where one decay chain \mathrm\ensuremathΩ^\ensuremath-\ensuremath→\mathrm\ensuremathΛK^\ensuremath- followed by \mathrm\ensuremathΛ\ensuremath→p\ensuremathπ^\ensuremath- is considered. Finally, we show that the inclusive angular distributions can be used to test spin assignment of the produced baryons.