Effective Action and Schwinger Pair Production in Scalar QED

Some astrophysical objects are supposed to have very strong electromagnetic fields above a critical strength. Quantum vacuum fluctuations due to strong electromagnetic fields modify the Maxwell theory and particularly electric fields make the vacuum unstable against pair production of charged particles. By finding the effective action, we study the strong field effect, the vacuum polarization due to the real part of the effective action and the Schwinger pair production due to the imaginary part of the effective action in scalar quantum electrodynamics (QED).The authors would like to thank Y. Yoon for useful discussions. The work of S. P. K. was supported by a Korea Research Foundation Grant funded by the Korean Government (Ministry of Education and Human Resources), KRF-2007-C00167 and the work of H. K. L. was supported by a Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (Ministry of Science and Technology), No. R01-2006-000-10651-0