Quasi-Feynman Rules for Calculating n-Point Correlators of the Primordial Curvature Perturbation
Rodriguez Garcia, Yeinzon (Universidad Antonio Narino & Universidad Industrial de Santander)

A diagrammatic approach to calculate n-point correlators of the primordial curvature perturbation \zeta was developed a few years ago following the spirit of the Feynman rules in Quantum Field Theory. The methodology is very useful and time-saving, as it is for the case of the Feynman rules in the particle physics context, but, unfortunately, is not very well known by the cosmology community. In the present work, we extend such an approach in order to include not only scalar field perturbations as the generators of \zeta, but also vector field perturbations. The purpose is twofold: first, we would like the diagrammatic approach (which we would call the quasi-Feynman rules) to become widespread among the cosmology community; second, we pretend to give an easy tool to formulate any correlator of \zeta for those cases that involve vector field perturbations and that, therefore, generate important levels of statistical anisotropy. Indeed, the usual way of formulating such correlators, using the Wick's theorem, may become very clutter and time-consuming.