Mustapha Lamaaoune, his research in theoretical and observational cosmology, with a focus on modified theories of gravity, dark energy phenomenology, and cosmological parameter estimation. His work explores extensions of General Relativity and their implications for early and late-time evolution of the Universe, cosmological tensions, and precision tests of gravity. His research for now is conducted through extensive analyses using current observational datasets, including Type Ia supernovae, Hubble parameter measurements, and combined cosmological probes. He actively contributes to international conferences and collaborative research efforts in cosmology and gravitational physics.