Soft Symmetry Breaking as a Nonstandard Source of Mass: Phenomenological Insights from the Two-Higgs-Doublet Model

TL;DR

This paper explores the role of the soft-breaking parameter in the Two-Higgs-Doublet Model, revealing it as a key indicator of high-energy symmetry breaking effects and analyzing how it influences nonstandard scalar masses.

Contribution

It introduces a novel interpretation of the soft-breaking parameter as a marker of high-energy symmetry breaking, distinct from the electroweak VEV, and proposes new parameters to quantify their contributions to scalar masses.

Findings

The soft-breaking parameter reflects high-energy symmetry breaking effects.

Nonstandard scalar masses are independently influenced by the soft-breaking parameter and electroweak VEV.

Current experimental data constrains the contribution of the electroweak VEV to nonstandard scalar masses.

Abstract

The soft-breaking parameter, $m_{12}^2$, frequently appearing in the 2HDM scalar potential is much more remarkable than being just a nonstandard parameter that helps make the BSM scalars super heavy. In fact, as we show through explicit calculations, it should be treated as the direct but concise embodiment of new non-electroweak spontaneous symmetry breaking effects at very high energy scales, wherein lies its quiddities. Consequently, it is argued that $m_{12}^2$ and the electroweak VEV serve as two distinct sources for the nonstandard scalar masses, which are completely unrelated to each other. Such distinctions allow us to define parameters that conveniently capture the fraction of the nonstandard scalar masses derived from the electroweak VEV. Finally, we demonstrate that constraints can already be placed on such fractions from the current measurements of the diphoton signal strength and from direct searches of new nonstandard scalar resonances in the diphoton channel.