Initial-State Radiation in Inclusive Photon Spectroscopy from Electron-Positron Annihilation

We demonstrate that the effect of the initial-state radiation can be observed in the inclusive photon spectrum from electron-positron annihilation by careful analysis of the data collected in a detector optimized for high resolution measurement of photons. We present the first example of a photon line from radiative corrections of the J/ψ, resonance at total center-of-mass energy far above its mass. We also discuss potential applications of such effect in future electron-positron experiments.