Production and dilution of gravitinos by modulus decay

We study the cosmological consequences of generic scalar fields like moduli which decay only through gravitationally suppressed interactions. We consider a new production mechanism of gravitinos from moduli decay, which might be more effective than previously known mechanisms, and calculate the final gravitino-to-entropy ratio to compare with the constraints imposed by successful big bang nucleosynthesis (BBN) etc., taking possible hadronic decays of gravitinos into account. We find the modulus mass smaller than [Formula Presented] is excluded. On the other hand, inflation models with high reheating temperatures [Formula Presented] can be compatible with BBN thanks to the late-time entropy production from the moduli decay if model parameters are appropriately chosen.