This work reports evidence for a deviation in the cosmic expansion history at high redshift (z ≳ 2) detected using Lyman-α (Lyα) baryon acoustic oscillation (BAO) measurements. Using Lyα BAO determinations of the Hubble parameter H (z), we test a phenomenological model in whichexpansion-rate residuals correlate with a cumulative information kernel Cum (z) =∫₀ᶻ C (z′) dz′. A statistically significant correlation is detected with amplitude A ≈ −37 km s⁻¹ Mpc⁻¹. The signal is robust under extensive falsification tests, including error re-weighting, tracersplitting, kernel scrambling, and explicit sound-horizon variation. Crucially, the deviation persists in an rd–independent Alcock–Paczyński analysis at >3σ significance, indicating a geometric origin independent of BAO ruler calibration. The repository includes the manuscript PDF, figures, and data tables used in the analysis.
V. Číhal (Sat,) studied this question.