Eur. Phys. J. C (2026) 86: 448
https://doi.org/10.1140/epjc/s10052-026-15684-2

Regular Article - Theoretical Physics

Probing reheating in a holographic induced gravity tachyon model with latest ACT constraints

¹ Laboratory of Physics of Matter and Radiation, University of Mohammed First, BP 717, Oujda, Morocco
² LMASI, Electromagnetism, Physics of Plasmas and Applications, Oujda, Morocco
³ Multidisciplinary Faculty of Nador, University of Mohammed First, BP. 300, Selouane, 62702, Nador, Morocco

^a This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 30 November 2025
Accepted: 5 April 2026
Published online: 2 May 2026

Abstract

In this study, we explore the reheating phase that follows tachyon inflation within the framework of holographic induced gravity (H-IG). Analytical relations for the reheating temperature $T_{\mathit{re}}$ and the reheating number of e-folds $N_{\mathit{re}}$ are derived under the assumption of a constant effective equation of state ${\omega }_{\mathit{re}}$. A numerical analysis is then performed over a broad range of model parameters namely c (holographic parameter), $\alpha$ (potential parameter), and $\gamma$ (IG parameter). Incorporating the most recent observational constraints from the Atacama Cosmology Telescope (ACT), which indicate a moderate upward shift in the scalar spectral index, $n_s$, relative to the Planck 2018 results, we reassess the viability of tachyon inflation with an exponential potential within this framework. Our analysis shows that when $\alpha$ is large ($\alpha \sim 2.5\times {10}^{-5})$, the majority of parameter combinations are consistent with observational constraints, though the best fit for the reheating duration $N_{\mathit{re}}$ to the data occurs for smaller c ($c\sim 1\times {10}^7$) and higher $\gamma$ ($\gamma \sim 0.9$) while also satisfying the lower bound on the reheating temperature $T_{\mathit{re}}$.