Observational constraints on the modified cosmology inspired by string T-duality

Abstract

We explore the cosmological consequences of a modified cosmology inspired by string T-duality. We incorporate the zero-point length correction, $l_0$, into the gravitational potential and derive the modified Friedmann equations via thermodynamic approach at the apparent horizon of a Friedmann-Robertson-Walker (FRW) universe. The resulting framework introduces a dimensionless coupling parameter $β\sim l_0^2H_0^2$ quantifying deviations from the standard $Λ$CDM model. Using Bayesian inference with \textsc{Cobaya} and MCMC sampling, we constrain the model parameter against late-time observations, including PantheonPlus and Union3 Type~Ia supernovae, cosmic chronometers, DESI~DR2 BAO measurements, and Amati-calibrated GRBs. The joint analysis yields an upper bound $β\lesssim \mathcal{O}(10^{-3})$ (68\% C.L.), implying that departures from $Λ$CDM are extremely small within current precision. Model comparison through the Akaike Information Criterion shows that the $Λ$CDM and T-duality models provide statistically equivalent fits to the data, exhibiting only a marginal preference for $Λ$CDM. These results provide the first quantitative observational constraints on string T-duality inspired modified cosmology and underscore the potential of future high-precision surveys to test quantum-gravity induced corrections in a late-time universe.