# Controlled Flavour Changing Neutral Couplings in Two Higgs Doublet Models

## TL;DR

This paper introduces a new class of Two Higgs Doublet Models with controlled tree-level Flavour Changing Neutral Currents, capable of satisfying experimental constraints and potentially explaining the Universe's baryon asymmetry.

## Contribution

It presents a novel class of 2HDMs allowing FCNC in both sectors with a discrete symmetry, avoiding fine-tuning and enhancing baryogenesis.

## Key findings

- Models respect experimental FCNC constraints without fine-tuning.
- Allow FCNC in both up and down sectors, unlike BGL models.
- Potentially enhance baryon asymmetry generation.

## Abstract

We propose a class of Two Higgs Doublet Models where there are Flavour Changing Neutral Currents (FCNC) at tree level, but under control due to the introduction of a discrete symmetry in the full Lagrangian. It is shown that in this class of models, one can have simultaneously FCNC in the up and down sectors, in contrast to the situation encountered in BGL models. The intensity of FCNC is analysed and it is shown that in this class of models one can respect all the strong constraints from experiment without unnatural fine-tuning. It is pointed out that the additional sources of flavour and CP violation are such that they can enhance significantly the generation of the Baryon Asymmetry of the Universe, with respect to the Standard Model.