Initial conditions for inflation and the energy scale of SUSY-breaking from the (nearly) gaussian sky

摘要

We show how general initial conditions for small field inflation can be obtained in multi-field models. This is provided by non-linear angular friction terms in the inflaton that provide a phase of non-slow-roll inflation before the slowroll inflation phase. This in turn provides a natural mechanism to star small-field slow-roll at nearly zero velocity for arbitrary initial conditions. We also show that there is a relation between the scale of SUSY breaking (√f) and the amount of nongaussian fluctuations generated by the inflaton. In particular, we show that in the local non-gaussian shape there exists the relation √f = 10~(13)GeV√fNL. With current observational limits from Planck, and adopting the minimum amount of nongaussian fluctuations allowed by single-field inflation, this provides a very tight constraint for the SUSY breaking energy scale √f = 3-7×10~(13) GeV at 95% confidence. Further limits, or detection, from next year's Planck polarisation data will further tighten this constraint by a factor of two. We highlight that the key to our approach is to identify the inflaton with the scalar component of the goldstino superfield. This superfield is universal and implements the dynamics of SUSY breaking as well as super-conformal breaking.