📝 SummarXiv

Abstract

In this work, we investigate a torsion-based cosmological model within the Einstei-Cartan framework, constrained by the latest combined datasets including DESI DR2 BAO, PantheonPlus and DESY5 supernovae, and the full Planck 2018 CMB measurements (temperature, polarization, and joint NPIPE PR4 + ACT DR6 lensing). The torsion parameter is constrained to $\alpha = -0.00066 \pm 0.00098$ with the full dataset combination, consistent with zero at less than $1\sigma$, while yielding a Hubble constant $H_0 = 68.41 \pm 0.32$ km/s/Mpc and matter clustering amplitude $S_8 = 0.812 \pm 0.006$. The model shows notable potential in alleviating cosmological tensions, reducing the $S_8$ discrepancy with KiDS-1000 from $\sim 2.3\sigma$ in $\Lambda$CDM to only $0.1\sigma$. Model comparisons based on the Akaike information criterion show consistent improvements across all datasets, with $\Delta {\rm AIC}$ values ranging from $-5.68$ to $-6.62$, indicating a statistically preferred fit for the torsion model. These results suggest that the torsion framework provides a physically well-motivated extension to $\Lambda$CDM, capable of simultaneously addressing key cosmological tensions while maintaining excellent agreement with diverse observational probes.