Abstract
Phys.Rev.D81:043508,2010 Dark matter decaying or annihilating into mu+mu- or tau+tau- has been
proposed as an explanation for the e+e- anomalies reported by PAMELA and Fermi.
Recent analyses show that IceCube, supplemented by DeepCore, will be able to
significantly constrain the parameter space of decays to mu+mu-, and rule out
decays to tau+tau- and annihilations to mu+mu- in less than five years of
running. These analyses rely on measuring track-like events in IceCube+DeepCore
from down-going nu_mu. In this paper we show that by instead measuring cascade
events, which are induced by all neutrino flavors, IceCube+DeepCore can rule
out decays to mu+mu- in only three years of running, and rule out decays to
tau+tau- and annihilation to mu+mu- in only one year of running. These
constraints are highly robust to the choice of dark matter halo profile and
independent of dark matter-nucleon cross-section.