Precision Higgsstrahlung as a Probe of New Physics

TL;DR

This paper explores how precise measurements of the Higgsstrahlung process at future electron-positron colliders can reveal new physics, using effective field theory and supersymmetric models to predict potential deviations.

Contribution

It provides a comprehensive EFT calculation including all relevant dimension-6 operators and a full one-loop analysis of third-generation squarks' effects on the Higgsstrahlung cross section.

Findings

EFT results match full one-loop calculations for large stop masses.

The study estimates the collider's sensitivity to new physics effects.

Results are applicable to models with high-scale new physics.

Abstract

A "Higgs factory", an electron-positron collider with center-of-mass energy of about 250 GeV, will measure the cross section of the Higgsstrahlung process, $e^+e^-\rightarrow hZ$, with sub-percent precision. This measurement is sensitive to a variety of new physics scenarios. In this paper, we study two examples. First, we compute corrections to the $e^+e^-\rightarrow hZ$ differential cross section in the effective field theory (EFT) approach, including the complete set of dimension-6 operators contributing to this process. These results are applicable to any model where the new physics mass scale is significantly above the weak scale. Second, we present a complete one-loop calculation of the effect of third-generation squarks, with arbitrary soft masses and mixing, on this cross section. This is expected to be the leading correction in natural supersymmetric models. We demonstrate the agreement between the full one-loop calculation and the EFT result in the limit of large stop masses. Finally, we estimate the discovery reach of the $e^+e^-\rightarrow hZ$ cross section measurement in the two models.