Torsion cosmology in the light of DESI, supernovae and CMB observational constraints

Abstract In this work, we investigate a torsion-based cosmological model within the Einstein CCartan 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 $$\alpha = -0.00066 \pm 0.00098$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>α</mml:mi> <mml:mo>=</mml:mo> <mml:mo>-</mml:mo> <mml:mn>0.00066</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.00098</mml:mn> </mml:mrow> </mml:math> with the full dataset combination, consistent with zero at less than $$1\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>1</mml:mn> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> , while yielding a Hubble constant $$H_0 = 68.41 \pm 0.32~\mathrm {km~s^{-1}~Mpc^{-1}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>H</mml:mi> <mml:mn>0</mml:mn> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>68.41</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.32</mml:mn> <mml:mspace/> <mml:mrow> <mml:mi>km</mml:mi> <mml:mspace/> <mml:msup> <mml:mi>s</mml:mi> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:mspace/> <mml:msup> <mml:mi>Mpc</mml:mi> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:mrow> </mml:math> and matter clustering amplitude $$S_8 = 0.812 \pm 0.006$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>S</mml:mi> <mml:mn>8</mml:mn> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>0.812</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.006</mml:mn> </mml:mrow> </mml:math> . The model shows notable potential in alleviating cosmological tensions, reducing the $$S_8$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>S</mml:mi> <mml:mn>8</mml:mn> </mml:msub> </mml:math> discrepancy with KiDS-1000 from $$\sim 2.3\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>∼</mml:mo> <mml:mn>2.3</mml:mn> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> in $$\Lambda $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Λ</mml:mi> </mml:math> CDM to only $$0.1\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>0.1</mml:mn> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> . Model comparisons based on the Akaike information criterion show consistent improvements across all datasets, with $$\Delta \textrm{AIC}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>Δ</mml:mi> <mml:mtext>AIC</mml:mtext> </mml:mrow> </mml:math> values ranging from $$-5.68$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>5.68</mml:mn> </mml:mrow> </mml:math> to $$-6.62$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>6.62</mml:mn> </mml:mrow> </mml:math> , indicating a statistically preferred fit for the torsion model. These results suggest that the torsion framework provides a physically well-motivated extension to $$\Lambda $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Λ</mml:mi> </mml:math> CDM, capable of simultaneously addressing key cosmological tensions while maintaining excellent agreement with diverse observational probes.