Study of the e+e− → π0γ process in the energy range 0.60 – 1.06 GeV

Abstract

The process e + e − → π 0 γ in the energy range √ s = 0.60 − 1.06 GeV was studied at VEPP-2M collider with SND detector using ∼ 14 pb −1 of integrated luminosity. Data were analyzed in the framework of the vector meson dominance model. Preliminary results on obtained cross-section and parameters of ρ 0 , ω, φ → π 0 γ radiative decays are presented.

Quantum interference of particles and resonances

“…The process (13) may provide a peak in the system K L p (or K S p), and one could not discriminate between Σ-like state (with S = −1) or Θ-like state (with S = +1). In contrast, a peak in the system K + n, expected in the process (14), has the tagged strangeness S = +1.…”

“…The process e + e − → π 0 γ also demonstrates direct interference of resonances ρ 0 , ω, and φ. Its cross section, measured by the SND group [10,14], is shown in figure 8. The energy dependence looks here similar to the case of 3π annihilation (figure 2).…”

“…8: The cross section of the process e + e − → π 0 γ. Data are measurements of the SND group [14], two fitting curves correspond to models with ρ 0 +ω +φ (solid) or ω +φ (dashed) intermediate states. Used with permission of the SND group.…”

“…Here, the two good resonances, φ and ∆, may enhance manifestation of Θ + . Note an interesting difference between processes (13) and (14). The process (13) may provide a peak in the system K L p (or K S p), and one could not discriminate between Σ-like state (with S = −1) or Θ-like state (with S = +1).…”

Production of π0ρ0 pair in electron-positron annihilation in the Nambu-Jona-Lasinio model

“…It is also concerned with a theoretical study of the process e + e − → π 0 ρ 0 within the ω−, ω ′ − and φ− mesons energy range. This process was recently measured at the CMD-2 detector at the VEPP-2M e + e − collider [1][2][3].…”