Extension of local-type inequality for the higher order correlation   functions
  For the local-type primordial perturbation, it is known that there is an inequality between the bispectrum and the trispectrum. By using the diagrammatic method, we develop a general formalism to systematically construct the similar inequalities up to any order correlation function. As an application, we explicitly derive all the inequalities up to six and eight-point functions. 
Teruaki Suyama and Shuichiro Yokoyama
astro-ph.CO hep-th