Speaker
Description
Future high-luminosity $e^+e^-$ colliders such as CEPC and FCCee will measure the Higgsstrahlung cross section $e^+e^- \to Zh$ with sub-percent precision, offering a unique window into probing extended scalar sectors. We present a complete one-loop electroweak calculation of this process in the real triplet Higgs model with a non--zero triplet vev, using a fully automated renormalisation procedure in the on--shell scheme. All counterterms, including those for the mixing angle between the real triplet and the doublet scalars and tadpoles in the PRTS scheme, are derived systematically, and the cancellation of UV and IR divergences is verified numerically with the help of FeynCalc and FormCalc. By constructing the ratio of the NLO BSM cross section to the SM prediction, we derive sensitivity contours in the plane of the triplet mass and the quartic coupling $a_2$, corresponding to the projected experimental precision of $0.26\%$. We further confront the model with the recent LHC hints for a $\sim 152$\,GeV di-photon resonance, which can be explained by the neutral component of the triplet. Our results demonstrate that precision Higgsstrahlung measurements at future lepton colliders provide complementary sensitivity to direct searches and can test the parameter regions favored by the LHC anomalies.
