Higher order nonlinear parameters with Planck constraints

We investigate how higher-order nonlinear parameters affect lower-order ones through loop effects. We calculate the loop corrections up to two loops and explicitly show that the tree contribution is stable against loop terms in most cases. We argue that, nevertheless, observational constraints on nonlinear parameters such as fNL and τNL can also give a limit even for higher-order ones due to the loop contribution. We discuss these issues for both single-source and multisource cases.