Radiative-corrected Higgs inflation in light of the latest ACT observations

Recent measurements from the Atacama Cosmology Telescope (ACT), particularly when combined with DESI baryon acoustic oscillation data, have reported a scalar spectral index ns slightly higher than that inferred by Planck 2018, suggesting a mild tension with the predictions of standard inflationary attractor models. In this work, we revisit the quantum-corrected Higgs inflation scenario within the framework of a non-minimally coupled scalar field theory. Starting from the one-loop effective action, we incorporate radiative corrections through the anomalous scaling parameter AI and derive analytic expressions for the inflationary observables ns and r in the Einstein frame. Our analysis demonstrates that quantum corrections naturally shift ns toward higher values while keeping the tensor-to-scalar ratio r suppressed. For N=60, the model predicts ns ≃ 0.9743 and r≃5.4×10−3, in excellent agreement with the latest ACT+DESI (P-ACT-LB) data and fully consistent with the Planck 2018 limit r < 0.036. The derived constraint 4.36×10−10<λ/ξ2<10.77×10−10 confirms the robustness of the quantum-corrected Higgs framework and indicates that near-future CMB polarization experiments such as CORE, AliCPT, LiteBIRD, and CMB-S4 will be able to probe the predicted parameter space with high precision.