2009/02/16 by NA60 Collaboration, R. Arnaldi, K. Banicz +46 · 147 citations
Chemistry · Physics and Astronomy · #Analytical Chemistry (journal) #Chemistry #Electron #High-Energy Particle Collisions Research #Lepton #Meson #Muon #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.1016/j.physletb.2009.05.029
published in Physics Letters B 677(5), 260-266 (Elsevier BV) · Submitted to Phys. Lett. B
arxiv created 2009/02/16 · openalex publication_date 2009/05/21 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158AGeV In–In collisions. The mass and pT spectra associated with peripheral collisions can quantitatively be described by the known neutral meson decays. The high data quality has allowed to remeasure the electromagnetic transition form factors of the Dalitz decays η→μ+μ−γ and ω→μ+μ−π0. Using the usual pole approximation F=(1−M2/Λ2)−1 for the form factors, we find Λ−2 (in GeV−2) to be 1.95±0.17(stat.)±0.05(syst.) for the η and 2.24±0.06(stat.)±0.02(syst.) for the ω. While the values agree with previous results from the Lepton-G experiment, the errors are greatly improved, confirming now on the level of 10σ the strong enhancement of the ω form factor beyond the expectation from vector meson dominance. An improved value of the branching ratio BR(ω→μ+μ−π0)=[1.73±0.25(stat.)±0.14(syst.)]×10−4 has been obtained as a byproduct.