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arXiv · 1903.07725

The $\hat{H}$-Parameter: An Oblique Higgs View

Christoph Englert·Gian F. Giudice·Admir Greljo·Matthew McCullough
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Abstract

We study, from theoretical and phenomenological angles, the Higgs boson oblique parameter $\hat{H}$, as the hallmark of off-shell Higgs physics. $\hat{H}$ is defined as the Wilson coefficient of the sole dimension-6 operator that modifies the Higgs boson propagator, within a Universal EFT. Theoretically, we describe self-consistency conditions on Wilson coefficients, derived from the K\"{a}ll\'{e}n-Lehmann representation. Phenomenologically, we demonstrate that the process $gg\to h^\ast \to VV$ is insensitive to propagator corrections from $\hat{H}$, and instead advertise four-top production as an effective high-energy probe of off-shell Higgs behaviour, crucial to break flat directions in the EFT.

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Christoph Englert, Gian F. Giudice, Admir Greljo, Matthew McCullough. 2019-03-18. The $\hat{H}$-Parameter: An Oblique Higgs View. https://doi.org/10.1007/jhep09(2019)041

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