Résumé
Phys. Rev. Research 7, L012018 (2025) We find that combined Planck cosmic microwave background, baryon acoustic oscillations and supernovae data analyzed under$\Lambda$ CDM are in 4.9 $\sigma$tension with eBOSS Ly $\alpha$forest in inference of the linear matter power spectrum at wavenumber$\sim 1 h\,\mathrm{Mpc}^{-1}$and redshift = 3. Model extensions can alleviate this tension: running in the tilt of the primordial power spectrum ( $\alpha_\mathrm{s} \sim -0.01$ ); a fraction$\sim (1 - 5)\%$of ultra-light axion dark matter (DM) with particle mass$\sim 10^{-25}$eV or warm DM with mass$\sim 10$eV. The new DESI survey, coupled with high-accuracy modeling, will help distinguish the source of this discrepancy.