Analysis of fine-tuning measures in models with extended Higgs sectors

Abstract

In the literature measures of fine-tuning have been discussed as one of the tools to assess the feasibility of beyond the Standard Model theories. In this paper we focus on two specific measures and investigate what kind of fine-tuning they actually quantify. First we apply both measures to the two Higgs doublet model, for which one can analyze the numerical results in terms of available analytic expressions. After drawing various conclusions about the finetuning measures, we investigate a particular left-right symmetric model for which it has been claimed that already at tree-level it suffers from a high amount of fine-tuning. We will reach a different conclusion, although left-right symmetric models may require a modest amount of fine-tuning if phenomenological constraints are imposed. Our analysis shows that the two considered measures can probe different aspects of fine-tuning and are both useful if applied and interpreted in the appropriate way. * d.boer@rug.nl

The electro-weak phase transition at colliders: confronting theoretical uncertainties and complementary channels

“…vestigate whether the introduction of additional interactions requires fine tuning of the parameters to achieve the observed Higgs boson mass. To do this, we employ the Barbieri-Giudice measure [160] (see also [161]):…”

“…This is in line with the tree-level studies of ref. [161], where it was pointed out that it is possible to have a large hierarchy of scales in theories with extended Higgs sectors, without having fine tuning.…”

The Electro-Weak Phase Transition at Colliders: Confronting Theoretical Uncertainties and Complementary Channels

“…It is therefore reasonable to investigate whether the introduction of additional interactions requires fine tuning of the parameters to achieve the observed Higgs boson mass. To do this, we employ the Barbieri-Giudice measure [128] (see also [129]): for a set of observables O i and a set of model parameters p j . One can roughly interpret the logarithm of ∆ as the number of significant digits that need to be tuned in at least one of the parameters of the theory.…”

“…This is in line with the tree-level studies of ref. [129], where it was pointed out that it is possible to have a large hierarchy of scales in theories with extended Higgs sectors, without having fine tuning.…”

Aspects of fine-tuning in theories with extended scalar sectors

“…As mentioned in Chapter 4. the Higgs sector of the 2HDM is constructed by adding an additional doublet to the Standard Model Higgs sector [44,81]. Recall that the two doublets are defined as:…”