Enhanced Electron-Positron Pair Production of a Vacuum in a Strong Laser Pulse Field by Frequency Variation

Effects of frequency variation on vacuum electron-positron pair production in strong pulsed laser fields are investigated in the framework of a quantum kinetic method. It is found that the slowly varying frequency can influence the pair production to some extent, while rapid varying frequency can increase the pair creation rate a few orders if the time lies within a narrow time window, in which frequency jump occurs. The possible physical mechanism behind the pair enhancement phenomenon is discussed briefly.