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 n s 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 A I and derive analytic expressions for the inflationary observables n s and r in the Einstein frame. Our analysis demonstrates that quantum corrections naturally shift n s toward higher values while keeping the tensor-to-scalar ratio r suppressed. For N = 60 , the model predicts n s ≃ 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 / ξ 2 < 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.