PARTICLE CREATION IN THE BELL-SZEKERES SPACETIME

The quantization of a real massless scalar field in a spacetime produc ed in a collision of two electromagnetic plane waves with constant wav efronts is considered. The background geometry in the interaction regi on, the Bell-Szekeres solution, is locally isometric to the conformall y flat Bertotti-Robinson universe filled with a uniform electric field . It is shown that before the waves interact the Bogoliubov coefficien ts relating different observers are trivial and no vacuum polarization takes place. In the non-singular interaction region neutral scalar pa rticles are produced with the number of created particles and spectrum typical of gravitational wave collision.