Constraints on cosmological parameters from future CMB experiments and lensing surveys

Anisotropies in the angular power spectra of the Cosmic Microwave Background (CMB) temperature and polarization have confirmed that we live in a Universe that agree with the theoretical predictions of the ΛCDM cosmology with great accuracy. Nevertheless there are many issues that have not yet found a solution, such as the H 0 and A lens tension, measuring the B-modes of Cosmic Microwave Background polarization and understanding the physics of dark energy. Future cosmological probes, like CMB-S4, LiteBIRD, Stage-III and CORE-M5, will have to deal with all of these. In the first part of this thesis we study the possibility of future experiments to constrain efficiently the amplitude of primordial tensor modes in presence of a primordial magnetic field. In the second part we discuss how they would be able to falsify the A lens tension and test a possible scale dependence of this parameter. In the last part instead we discuss the constraints that could be achieved on the dark energy equation of state combining together gravitational waves, CMB and strong lensing data.