The η_cγ γ ^* transition form factor in the decay η_c→ γ ℓ⁺ℓ^- and in the crossed channels γ e^-→ η_c e^- and e⁺e^-→η_cγ

2000/04/12 by E. Di Salvo, Elvio Di Salvo, M.P. Rekalo +3 · 2 citations
Physics and Astronomy · #Basis (linear algebra) #Distribution (mathematics) #Form factor (electronics) #Lepton #Particle physics theoretical and experimental studies #Photon #Quantum Chromodynamics and Particle Interactions #Quantum and Classical Electrodynamics #Spectrum (functional analysis) #Vertex (graph theory) #Zero (linguistics) #hep-ph

paper · pdf · doi:10.1007/s100520050022

published in The European Physical Journal C 16(2), 295-302 (Springer Science+Business Media) · 20 pages, 9 figures

arxiv created 2000/04/12 · openalex publication_date 2000/08/01 · arxiv updated 2011/09/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

The Dalitz distribution and the effective mass spectrum of the lepton pair produced in the decay η_c→ γℓ⁺ ℓ^-, as well as the differential cross sections for the crossed channels γe^-→ η_c e^- and e⁺ e^-→ η_c γ, are calculated in terms of the sole electromagnetic transition form factor for the vertex η_c→γγ^*, where γ^* is a virtual photon with a space-like (for γe^- → η_c e^- ) or a time-like (for e⁺ e^-→ η_c γ and η_c→γℓ⁺ℓ^-) four-momentum. Explicit parametrisations of the transition form factor are found in two different approaches, namely in Vector Dominance Model and in a QCD-inspired consideration on the basis of the process c c→ γℓ⁺ ℓ^-, with zero relative three-momentum of the annihilating quarks.

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• Form factors of η c in light-front quark model