High Energy Physics Seminar on 15th July (Sen)

[HECAP - Margherita Di Giovannantonio]

*_HIGH ENERGY PHYSICS SEMINARS_**__*


*Tuesday, 15 July *2025, at *16:00* - *Luigi Stasi Seminar Room **- 
https://indico.ictp.it/event/10988/*

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Anjan Ananda Sen (Centre For Theoretical Physics - Jamia Millia Islamia 
Central University)



*“Geometric Determinations of Characteristic Redshifts from DESI-DR2 BAO 
and DES-SN5YR Observations: Hints For New Expansion Rate Anomalies"*
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_Abstract_
n this talk, I shall present our recent ongoing work on  a 
model-agnostic reconstruction of the cosmic expansion history by 
combining DESI-DR2 BAO and DES-SN5YR data, with a focus on geometric 
determination of characteristic redshifts where notable tensions in the 
expansion rate are found to emerge. Employing Gaussian process 
regression alongside knot-based spline techniques, we reconstruct cosmic 
distances and their derivatives to pinpoint these characteristic 
redshifts and infer $E(z)= \frac{H}{H_{0}$. Our study reveals 
significant deviations of approximately 4 to 5 $\sigma$ from the Planck 
2018 $\Lambda$CDM predictions, particularly pronounced in the redshift 
range $ z < 1$. These anomalies are consistently observed across both 
reconstruction methods and combined datasets, indicating robust 
late-time departures that could signal new physics beyond the standard 
cosmological framework.

The joint use of BAO and SN probes enhances the precision of our 
constraints, allowing us to isolate these deviations without reliance on 
specific cosmological assumptions. Our findings underscore the role of 
characteristic redshifts as sensitive indicators of expansion rate 
anomalies and motivate further scrutiny with forthcoming datasets from 
DESI-5YR BAO, Euclid, and LSST.



To join via Zoom:
https://zoom.us/j/98935069843

Meeting ID: 989 3506 9843

Passcode : 842099