Speaker
Summary
The most popular class of candidates for dark matter are
the stable
weakly interacting massive particles (WIMPs), which
arise in many
well-motivated TeV scale extensions of the standard
model. Their stability
is guaranteed by some symmetries. However in most
models,
the energy densities of normal matter
and dark matter are unrelated. In this talk, I review a
model of
asymmetric dark matter we proposed recently, in which
the dark sector
is an identical copy of both forces and matter of the
standard model (SM) as in the mirror
universe models discussed in literature. In addition to
being connected by gravity, the SM and
DM sectors are also connected at high temperature by a
common set
of heavy right-handed Majorana neutrinos via their
Yukawa
couplings to leptons and Higgs bosons. The lightest
nucleon in the
dark (mirror) sector is a candidate for dark matter. The
out of
equilibrium decay of right-handed neutrino produces
equal lepton
asymmetry in both sectors via resonant leptogenesis
which then get
converted to baryonic and dark baryonic matter. A
kinetic mixing between the
$U(1)$ gauge fields of the two sectors is introduced to
guarantee the
success of Big-Bang Nucleosynthesis and make the
direct detection of
the mirror dark matter possible. We explore how this
model can be tested in direct search experiments. In
particular,
we point out that if the dark matter happens to be the
mirror
neutron, the direct detection cross section has the
unique feature
that it increases at low recoil energy unlike the case of
conventional WIMPs. It is also interesting to note that
the
predicted spin-dependent scattering could make
significant
contribution to the total direct detection rate, especially
for
light nucleus. With this scenario, one could explain
recent DAMA and CoGeNT results.
