Chasing the two-Higgs-doublet model via electroweak corrections at $e^+e^-$ colliders

Abstract

We present a comprehensive study of Higgs boson production associated with a neutrino pair at $e^+e^-$ colliders ($e^+ e^- \to h \, ν\barν$) at next-to-leading-order accuracy in both the Standard Model and the two-Higgs-doublet model. We show that these new physics effects will be observable in total and differential cross sections when compared with theoretical predictions that include electroweak corrections, even in the Higgs alignment limit. This highlights the potential of precision studies at future $e^+e^-$ colliders for searching new physics.

Figures (5)

• Figure 1: Diagrams for $e^+ e^- \to h \, \nu \bar{\nu}$ at NLO EW in 2HDM.
• Figure 2: Top panel: differential cross sections at NLO as a function of the normalised Higgs three-momentum $\bar{p}_h\equiv|\vec{p}_h|/\sqrt{s}$ at $\sqrt{s}=365\,$GeV (orange) and $\sqrt{s}=550\,$GeV (blue), in the SM (dashed) and 2HDM (solid). Bottom panel: ratios of the 2HDM predictions to the SM ones at NLO.
• Figure 3: Type I, II, X and Y 2HDM predictions in the $\cos(\beta-\alpha)$ plane at $\sqrt{s} = 365$ GeV within the allowed parameter space, with $|\cos(\beta-\alpha)|<0.1$. Relative differences with respect to the SM are shown at LO (red) and NLO (orange for $|\lambda_5|<1$, blue for $|\lambda_5|\geq 1$). The combined theoretical and experimental uncertainty is estimated to be 0.92%.
• Figure 4: Type I 2HDM predictions in the $\lambda_5$, $\tan(\beta)$, $\cos(\alpha)/\sin(\beta)$ and $m_{\phi}$ parameter planes at $\sqrt{s} = 365$ GeV within the allowed parameter space, with $|\cos(\beta-\alpha)|<0.1$.
• Figure 5: Type I 2HDM predictions at $\sqrt{s} = 550$ GeV within the allowed parameter space, with $|\cos(\beta-\alpha)|<0.1$. The combined theoretical and experimental uncertainties are estimated to be 0.85%.