Graceful exit from a stringy landscape via MSSM inflation

The cosmological evolution of the string landscape is expected to consist of multiple stages of old inflation with large cosmological constant ending by tunneling. Old inflation has a well known graceful exit problem as the observable universe becomes empty, devoid of any entropy. Simultaneously, in the quest for reheating the right degrees of freedom, it is important that the final stage of inflation ends within the Minimal Supersymmetric Standard Model (MSSM) sector. In this paper, we study how inflation of a MSSM flat direction can be embedded into the string theory landscape of metastable vacua. The fluctuations of the MSSM flat direction during old inflation create regions with initial conditions favorable for eternal and slow-roll inflation and provides a graceful exit from old inflation on the landscape. This resulting phase of MSSM inflation generates enough e-foldings of inflation to dilute any relics of old inflation while producing the observed amplitude of temperature anisotropy with a matching spectral tilt and negligible gravity waves. The decay of the flat direction reheats the universe, which is suitable for a hot big bang cosmology filled with Standard Model baryons and cold dark matter.