Top panel: energy spectrum of relativistic leptons, calculated for direct shock acceleration of electrons (electron index p = 2) and for secondary pairs from pion decay (proton index p = 2). Bottom panel: synchrotron emissivity as a function of frequency for the particle spectra in the top panel. The thermal free–free emissivity is shown for comparison. Calculations were performed adopting the best-fitting shock parameters for V1324 Sco (Table 4) of v₈ = 0.63, ϵ_e = 0.08, f_EUV = 0.05 at the 10 GHz maximum (t = 71.5 d, n₄ = 4.5 × 10⁶ g cm⁻³).