Particle Physics and Cosmology with H.E.S.S.

Gamma-ray astronomy is a powerful mean of studying particle physics and cosmology independently of particle colliders and more conventional observatories. In a 50 GeV-50 TeV range, observations of Galactic and extragalactic high-energy sources allow to efficiently search for new particles such as dark matter particles and axions; they probe the UV to infrared backgrounds of the universe whose energy density is linked to star formation and evolution of structures; and they permit to test Lorentz invariance up to the Planck scale. This report focues on some recent results in these matters obtained with the H.E.S.S. array of Cherenkov telescopes.