A parametric reconstruction of cosmic acceleration in f(T,B) gravity with a new Hubble ansatz

In this work, we explore a generalized teleparallel gravity model described by [Formula: see text] which is constructed to explain late-time cosmic acceleration without relying on a cosmological constant. To address the complexity of the field equations, we adopt a parametrized Hubble function [Formula: see text] using the latest observational datasets — Cosmic Chronometers, Baryon Acoustic Oscillations (BAO), DESI DR2 BAO and Pantheon+ Supernovae. We obtain the best-fit parameters consistent with current data. The model predicts a smooth deceleration to acceleration transition at redshift [Formula: see text], a present deceleration parameter of [Formula: see text], and a present equation of state [Formula: see text]. The estimated age of the Universe, [Formula: see text] Gyr, closely agrees with Planck 2018 results. Furthermore, linear perturbation analysis of the energy density and Hubble parameter demonstrates that fluctuations remain bounded across the cosmic timeline, which ensures the dynamical stability of the model. Overall, the framework provides a viable, stable and observationally consistent description of cosmic acceleration.