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arXiv · 2606.21839

Observational Constraints on $f(Q,T)$ Gravity in the Presence of DBI-Essence Scalar Field

Mayur Mune·Praveen Kumar Dhankar·Goutam Manna·Safiqul Islam·Bidisha Samanta·Behnam Pourhassan
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Abstract

We investigate late-time cosmology in extended symmetric teleparallel gravity coupled to a Dirac-Born-Infeld (DBI) scalar field within $f(Q,T)$ gravity, where $Q$ is the non-metricity scalar and $T$ is the trace of the matter energy-momentum tensor. Working on a spatially flat Friedmann-Lemaître-Robertson-Walker background and treating the cosmic medium as an effective perfect fluid, we derive the background field equations for $f(Q,T)+\mathrm{DBI}$ gravity and obtain analytic solutions for the linear choice $f(Q,T)=αQ+βT$. We then constrain the model parameters with a Markov Chain Monte Carlo analysis using Hubble-rate data, DESI BAO (DR2) measurements, and the Pantheon+SHOES Type~Ia supernova sample. The joint posteriors (Tables II and III) are broadly consistent with current late-time constraints and allow a direct comparison with $Λ$CDM, quantifying the departures driven by the $βT$ coupling and the DBI sector. Although the model does not reproduce every observational feature exactly, it provides a statistically viable alternative avenue to the standard paradigm and a useful framework for exploring potential remedies to existing tensions, including the $H_0$ discrepancy, without claiming a definitive resolution.

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Mayur Mune, Praveen Kumar Dhankar, Goutam Manna, Safiqul Islam, Bidisha Samanta, Behnam Pourhassan. 2026-06-20. Observational Constraints on $f(Q,T)$ Gravity in the Presence of DBI-Essence Scalar Field. https://arxiv.org/abs/2606.21839

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