Singlet Model Interference Effects with High Scale UV Physics

TL;DR

This paper investigates how interference between a scalar singlet resonance and effective field theory operators can significantly alter Higgs boson signals, revealing complex effects that challenge simple models and impact interpretations of experimental data.

Contribution

It demonstrates the importance of considering interference effects between singlet scalars and EFT operators, showing they can cause cancellations and affect Higgs coupling fits.

Findings

Interference effects can significantly modify Higgs signals.

Large cancellations between resonance and EFT contributions are possible.

Simplistic models may be invalidated by these interference effects.

Abstract

One of the simplest extensions of the Standard Model (SM) is the addition of a scalar gauge singlet, S. If S is not forbidden by a symmetry from mixing with the Standard Model Higgs boson, the mixing will generate non-SM rates for Higgs production and decays. In general, there could also be unknown high energy physics that generates additional effective low energy interactions. We show that interference effects between the scalar resonance of the singlet model and the effective field theory (EFT) operators can have significant effects in the Higgs sector. We examine a non-$Z_2$ symmetric scalar singlet model and demonstrate that a fit to the 125 GeV Higgs boson couplings and to limits on high mass resonances, S, exhibit an interesting structure and possible large cancellations of effects between the resonance contribution and the new EFT interactions, that invalidate conclusions based on the renormalizable singlet model alone.