The Standard Model of particle physics can be extended by a number of hidden sector models whose messenger particles interact only very weakly with the Standard Model. Consequently, the mass of these messenger particles is usually not constrained and they can appear in experiments at very different energy scales. The Standard Model degrees of freedom at these energy scales are captured by different effective field theories. I present a systematic extension of the SM effective field theories with portal operators to hidden sectors. As a concrete example I show how to derive decay amplitudes into messenger particles using portal chiral perturbation theory.
[The seminar will be recorded]
With support from FCT through project UIDB/00777/2020