# A New ~ 5σ Tension at Characteristic Redshift from DESI-DR1 BAO and DES-SN5YR Observations

arXiv: https://arxiv.org/abs/2503.02880 · HTML: https://mlsanity.com/paper/2503.02880/

## Key facts

- No citing papers in the map yet (data through 14 Oct 2026).
- Builds on 5 of its 82 references that are in the map.
- First posted on arXiv 4 Mar 2025.

## Builds on (most cited first, 5 of 5)

- [Pyro: Deep Universal Probabilistic Programming](https://mlsanity.com/paper/1810.09538/) (2018)
- [Composable Effects for Flexible and Accelerated Probabilistic Programming in NumPyro](https://mlsanity.com/paper/1912.11554/) (2019)
- [Model-independent cosmological inference post DESI DR1 BAO measurements](https://mlsanity.com/paper/2405.19178/) (2024)
- [Model-Agnostic Cosmological Inference with SDSS-IV eBOSS: Simultaneous Probing for Background and Perturbed Universe](https://mlsanity.com/paper/2412.13973/) (2024)
- [Deep Learning Based Recalibration of SDSS and DESI BAO Alleviates Hubble and Clustering Tensions](https://mlsanity.com/paper/2412.14750/) (2024)

## Abstract (arXiv)

We perform a model-independent reconstruction of the angular diameter distance (DA) using the Multi-Task Gaussian Process (MTGP) framework with DESI-DR1 BAO and DES-SN5YR datasets. We calibrate the comoving sound horizon at the baryon drag epoch rd to the Planck best-fit value, ensuring consistency with early-universe physics. With the reconstructed DA at two key redshifts, z~ 1.63 (where DAprime =0) and at z~ 0.512 (where DAprime = DA), we derive the expansion rate of the Universe H(z) at these redshifts. Our findings reveal that at z~ 1.63, the H(z) is fully consistent with the Planck-2018 LambdaCDM prediction, confirming no new physics at that redshift. However, at z ~ 0.512, the derived H(z) shows a more than 5σ discrepancy with the Planck-2018 LambdaCDM prediction, suggesting a possible breakdown of the LambdaCDM model as constrained by Planck-2018 at this lower redshift. This emerging ~ 5σ tension at z~ 0.512, distinct from the existing ``Hubble Tension'', may signal the first strong evidence for new physics at low redshifts.