Electroweak radiative corrections to $e^+e^- \to t \bar{t} h$ at linear colliders
You Yu, Ma Wen-Gan, Chen Hui, Zhang Ren-You, Sun Yan-Bin, Hou Hong-Sheng
TL;DR
Problem: precise prediction of $e^+e^- \to t\bar t h$ at linear colliders to measure the top Yukawa coupling. Approach: compute the full ${\cal O}(\alpha_{\rm ew})$ electroweak corrections, including virtual one-loop diagrams and real photon emission, with dimensional regularization and the complete on-mass-shell renormalization scheme, using FeynArts/Form and phase-space slicing for bremsstrahlung. Key findings: corrections are large and highly dependent on $m_h$ and $\sqrt{s}$, e.g., up to about $-31.3\%$ at 500 GeV for $m_h=150$ GeV and up to $+2.3\%$ at 2 TeV, with threshold spikes near $m_h=2m_W$ and $2m_Z$. Significance: these EW effects are essential for reliable SM predictions and for robust extraction of the top Yukawa coupling at future linear colliders.
Abstract
We calculate the ${\cal O}(α_{\rm ew})$ electroweak radiative corrections to $e^+ e^- \to t \bar{t} h$ at a electron-positron linear collider (LC) in the standard model. We analyze the dependence of the ${\cal O}(α_{\rm ew})$ corrections on the Higgs boson mass $m_{h}$ and colliding energy $\sqrt{s}$, and find that the corrections significantly decrease or increase the Born cross section depending on the colliding energy. The numerical results show that the ${\cal O}(α_{\rm ew})$ relative correction is strongly related to the Higgs boson mass when $\sqrt{s}=500 GeV$, and for $m_h = 150 GeV$ the relative correction ranges from -31.3% to 2.3% as the increment of the colliding energy from 500 GeV to 2 TeV.