Positron and electron peaks produced by sub-Coulomb barrier heavy-ion collisions are studied in terms of a new neutral particle (φ) production together with its decay into the electron-positron pair. The φ-production cross section is calculated in the semiclassical method, assuming a spinless φ and ignoring the Doppler broadening. The φ couplings to charged leptons are two orders of magnitude larger than that expected from their (g−2). The identification of φ as the axion is ruled out for the minimal standard theory by Weinberg-Wilczek. If we take seriously the small Doppler broadenings of positron and electron peaks observed in the experiment, we cannot retain the origin of the peaks to be due to a particle φ. Other possible origins of the peaks are discussed.