Tuned Two-Higgs-Doublet Model

TL;DR

This paper explores a Two-Higgs-Doublet Model constrained by divergence cancellation, analyzing its parameter space, CP violation potential, and implications for the hierarchy problem, showing it can extend naturalness up to about 2.5 TeV.

Contribution

It introduces a 2HDM framework with divergence cancellation up to two loops, detailing parameter regions compatible with experiments and CP violation, and demonstrating its ability to address the little hierarchy problem.

Findings

Parameter space consistent with experimental constraints identified.

Regions with significant CP violation found.

Model extends natural cutoff scale from 0.6 TeV to about 2.5 TeV.

Abstract

We consider a Two-Higgs-Doublet Model (2HDM) constrained by the condition that assures cancellation of quadratic divergences up to the leading two-loop order. Regions in the parameter space consistent with existing experimental constraints and with the cancellation condition are determined. The possibility for CP violation in the scalar potential is discussed and regions of \tan_\beta-M_{H^\pm} with substantial amount of CP violation are found. The model allows to ameliorate the little hierarchy problem by lifting the minimal scalar Higgs boson mass and by suppressing the quadratic corrections to scalar masses. The cutoff originating from the naturality arguments is therefore lifted from ~0.6 TeV in the Standard Model to ~2.5 TeV in the 2HDM, depending on the mass of the lightest scalar.