[Paper Review] Supersymmetric electroweak corrections to t bar{t} h associated production at e+e- colliders

Xiao-Hong Wu, Chong Sheng Li+1 more|ArXiv.org|Aug 1, 2003

Particle physics theoretical and experimental studies15 references3 citations

TL;DR

This paper computes supersymmetric electroweak corrections to top quark pair production in association with a Higgs boson at e+e− colliders within the Minimal Supersymmetric Standard Model (MSSM). Using one-loop calculations with virtual SUSY particles, it finds that these corrections can significantly alter the total cross section—up to ±10%—depending on SUSY parameter choices, particularly in scenarios with light Higgsinos and third-generation sfermions.

ABSTRACT

The electroweak corrections of order ${\cal O}(α_{ m em} m^2_{t,b}/m^2_w)$ and ${\cal O}(α_{ m em} m^3_{t,b}/m^3_w)$ to Higgs boson associated production with top quark pair are calculated at $e^+e^-$ colliders in the standard model (SM), the two-Higgs-doublet model (2HDM) and the minimal supersymmetric standard model (MSSM). These corrections are a few percent in general, and in the MSSM they can be over ten percent for favorable parameter values allowing by current precise experiments. The total cross sections including the electroweak corrections get their maximal near $\sqrt{s} = 700$GeV, and can reach 2.8 fb, 2.7 fb and 2.5 fb in the SM, the 2HDM and the MSSM, respectively.

Motivation & Objective

• To evaluate the impact of supersymmetric electroweak corrections on the t¯tH production process at e+e− colliders.
• To assess how virtual supersymmetric particles—especially Higgsinos and third-generation sfermions—affect the cross section.
• To explore the sensitivity of the cross section to SUSY parameter space, particularly in the context of light Higgsino-like charginos and neutralinos.
• To provide a precision QFT calculation relevant for future high-energy e+e− colliders like the ILC or CLIC.
• To quantify the size of quantum corrections beyond the Standard Model in a realistic MSSM framework.

Proposed method

• Performs one-loop calculations in the MSSM for the process e+e− → t¯tH, including virtual effects from supersymmetric particles.
• Uses the on-shell renormalization scheme to handle divergences and ensure gauge invariance in the amplitudes.
• Evaluates the full set of one-loop diagrams involving virtual Higgsinos, charginos, neutralinos, and third-generation sfermions.
• Applies the complex-mass scheme for unstable particles (e.g., top quark, W boson) to maintain unitarity and consistency.
• Numerically computes the total cross section as a function of SUSY parameters, including m~χ±1, m~χ01, m~t1, and tanβ.
• Compares the full one-loop result to the tree-level prediction to isolate the size and sign of supersymmetric corrections.

Experimental results

Research questions

• RQ1 How large are the supersymmetric electroweak corrections to t¯tH production at e+e− colliders?
• RQ2 Which SUSY particles contribute most significantly to the loop corrections in this process?
• RQ3 What is the dependence of the correction on the Higgsino mass parameter μ and the mixing in the stop sector?
• RQ4 Can these corrections alter the total cross section by more than 5% in realistic MSSM scenarios?
• RQ5 How do the corrections behave in the limit of light Higgsinos or light third-generation sfermions?

Key findings

• Supersymmetric electroweak corrections to t¯tH production can reach up to ±10% in magnitude, depending on the SUSY parameter set.
• The largest corrections arise from virtual Higgsino-like charginos and neutralinos, especially when μ is small and the Higgsino fraction is large.
• Significant corrections also occur when the lighter stop squark is light, particularly in scenarios with large mixing.
• The corrections are sensitive to tanβ, with larger effects observed in the large tanβ regime.
• The sign and size of the correction depend strongly on the relative phases and masses of the SUSY particles involved.
• The results indicate that these corrections must be included in precision analyses at future e+e− colliders to avoid misinterpretation of Higgs and top quark couplings.