Supersymmetric topological inflation model

We propose a topological inflation model in supergravity. In this model, the vacuum expectation value (VEV) of a scalar field takes a value much larger than the gravitational scale ${M}_{G}\ensuremath{\simeq}2.4\ifmmode\times\else\texttimes\fi{}{10}^{18} \mathrm{GeV},$ which is large enough to cause topological inflation. On the other hand, expansions of the K\"ahler potential and the superpotential beyond the gravitational scale are validated by the introduction of a Nambu-Goldstone-like shift symmetry. Thus, topological inflation inevitably takes place in our model.