Gauge-invariant inflaton in the minimal supersymmetric standard model

We argue that all the necessary ingredients for successful inflation are present in the flat directions of the Minimally Supersymmetric Standard Model. We show that out of many gauge-invariant combinations of squarks, sleptons, and Higgs bosons, there are two directions, $\mathbf{L}\mathbf{L}\mathbf{e}$ and $\mathbf{u}\mathbf{d}\mathbf{d}$, which are promising candidates for the inflaton. The model predicts more than ${10}^3$ $e$-foldings, with an inflationary scale of $H_{\inf }\sim \mathcal{O}(1–10)\mathrm{GeV}$, provides a tilted spectrum with an amplitude of ${\delta }_H\sim {10}^{-5}$ and a negligible tensor perturbation. The temperature of the thermalized plasma could be as low as $T_{rh}\sim \mathcal{O}(1–10)\mathrm{TeV}$. Parts of the inflaton potential can be determined independently of cosmology by future particle physics experiments.