2005/01/24 by Marek Karliner, Harry J. Lipkin
Mathematics · Physics and Astronomy · #Angular momentum #Atomic physics #Classical mechanics #Distribution (mathematics) #Geometry #High-Energy Particle Collisions Research #Invariant (physics) #Invariant mass #Mathematical analysis #Mathematics #Nuclear physics #Parity (physics) #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Reflection symmetry #Resonance (particle physics) #Symmetry (geometry) #Total angular momentum quantum number #hep-ex #hep-ph #nucl-ex
paper · pdf · doi:10.1016/j.physletb.2005.04.048
published in Physics Letters B 616(3-4), 191-195 (Elsevier BV) · Following readers' comments, stressing applicability to both fixed target and collider exps, in both Theta^+ and Theta_c searches, especially with low stats; reflected also in title change
arxiv created 2005/01/24 · openalex publication_date 2005/05/05 · arxiv updated 2010/04/05 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The distribution of the squared momentum difference |PA|2−|PB|2 between the momenta in the laboratory system of two experimentally observed particles A and B provides a test for whether an observed mass peak indicates a real resonance rather than nonresonant background or kinematic reflection. The angular distribution of the relative momenta in the center-of-mass system exhibits a forward–backward symmetry in the production and decay of any resonance with a definite parity. This symmetry is not expected in other nonresonant processes and can be expressed without needing angular distributions in terms of the easily measured momenta in the laboratory frame that are already measured and used to calculate the invariant mass of the system. Our test is especially useful for low statistics experiments where the full angular distribution cannot be determined. It can be applied to both fixed-target and collider searches for the Θ+ and Θc pentaquarks.