PARTICLE-PRODUCTION IN DE SITTER SPACE

Partial creation in de Sitter spacetime is studied in a complex-time W KB approximation. It is found that the particle production parallels t he description of particle creation by a collapsing spherical body. Th e appropriate vacuum for an inflationary early universe is the Hartle- Hawking vacuum; this is also a general feature of expanding spacetimes . The effect of particle production back on the metric is treated in a way that differs from the standard semiclassical approach.