Dark matter with time-varying leptophilic couplings

Two general problems arise when interpreting the recent cosmic ray data as signals of dark matter (DM) annihilation: (i) the required cross section is too large by O(100), and (ii) the annihilation products seem to be mostly leptonic. We propose to address these two problems by assuming that the couplings of DM to leptons grow with time. This can be achieved by a dynamic localization of DM in extra dimensions. A possible outcome of this proposal is a time (redshift) dependent annihilation signal, in terms of strength and dominant final states.