Searches for leptophilic dark matter with astrophysical experiments

One of the most exciting goals of particle and astroparticle physics is the understanding of the nature of dark matter (DM). A huge experimental effort is made to detect DM, under the assumption that some interaction with Standard Model particles exists, besides gravitation. In particular, DM in our Galaxy might annihilate into standard model particles and provide an additional contribution to cosmic ray fluxes. Precise measurements of the cosmic rays fluxes are therefore crucial. The AMS-02 experiment measures the fluxes of charged cosmic rays with unprecedented precision. From the theory side, viable dark matter candidates are provided both as byproducts of well motivated extensions of the standard model and by minimal models. Cosmic rays measurements can be used to probe these DM models. For this, two ingredients are necessary. First, appropriate predictions for the fluxes due to dark matter annihilation in the Galaxy are needed. Second, to be able to detect this exotic cosmic rays contributions, a reliable description of the fluxes of astrophysical origin is required. In this work, we focus on a specific class of DM models, the so-called leptophilic models, where DM annihilates at tree-level only into electron-positron pairs. We first discuss the importance of the inclusion of electroweak (EW) radiation for the theoretical predictions for the DM-induced cosmic ray fluxes. In particular, we study the range of applicability and limitations of a model-independent formalism to include the emission of EW gauge bosons. The inclusion of EW radiation is particularly relevant for leptophilic models, as it induces fluxes of hadrons, neutrinos and photons, that would otherwise be neglected. We then introduce a phenomenological model for the electron and positron fluxes of astrophysical origin. Under the assumption that the energy spectra of astrophysical fluxes are smooth, this model describes them with twelve parameters. We determine these parameters by fitting the model to the AMS-02 measurements of electron and positron fluxes. Dark matter annihilation in the Galaxy would induce additional spectral features on top of the smooth background. Given the absence of statistically significant spectral features in the AMS-02 measurements, we derive new upper limits on the DM annihilation cross section for leptophilic models in general. Assuming that the DM annihilation cross section is close to this upper limit, we obtain predictions for the expected antiproton flux due to the decay of EW gauge bosons. These fluxes can be compared to available measurements. Finally, we briefly study leptophilic DM at the Large Hadron Collider. We consider a specific model and compute the DM production cross section, that is loop-induced in the scenario under study