Salati, Pierre2017-05-232017-05-232017-05https://hdl.handle.net/11299/188211The nature of dark matter, an essential component of the Universe, is still unresolved. The best candidate is a weakly interacting particle yet to be discovered at accelerators. In most models, these exotic species annihilate and yield in particular antiprotons and positrons, hence the connection between the dark matter problem and antimatter cosmic rays. Distortions and anomalies in the antiproton and positron spectra are actively searched. A positron excess has actually been discovered and recently confirmed. But claiming that dark matter species have been discovered in the cosmic radiation requires to understand it and to properly model the various backgrounds in which the signal might be found. To achieve this goal, a key ingredient is the transport of charged particles within the magnetic halo of the Milky Way. In this talk, I will focus on a few (semi)-analytic methods used to solve the transport of cosmic rays and derive their fluxes at the Earth. I will then describe the so-called pinching method, which allows for a fast and reliable calculation of the positron spectrum even at low energies. Finally, with the help of this new tool, I will reinvestigate if dark matter can source the positron excess and I will set limits on MeV dark matter candidatesenFTPIOLIVEFESTPresentation