  We study the potential impact of detecting the inflationary gravitational
wave background by the future space-based gravitational wave detectors, such as
DECIGO and BBO. The signal-to-noise ratio of each experiment is calculated for
chaotic/natural/hybrid inflation models by using the precise predictions of the
gravitational wave spectrum based on numerical calculations. We investigate the
dependence of each inflation model on the reheating temperature which
influences the amplitude and shape of the spectrum, and find that the
gravitational waves could be detected for chaotic/natural inflation models with
high reheating temperature. From the detection of the gravitational waves, a
lower bound on the reheating temperature could be obtained. The implications of
this lower bound on the reheating temperature for particle physics are also
discussed.
