  In the scenario of isospin-violating dark matter (IVDM), the dark matter (DM)
spin-independent couplings to protons and to neutrons are allowed to be
different, which has been considered to relax the tensions between the results
of DAMA, CoGeNT and XENON experiments. We explore the allowed values of
DM-nucleon couplings favored and excluded by the current experiments under the
assumption of IVDM. We find that the recently updated XENON100 result excludes
the main part of the overlapping signal region between DAMA and CoGeNT. The
mass of the IVDM is restricted to a narrow range near 7.5-8 GeV. We also show
that the possible tensions between some experiments such as that between DAMA
and SIMPLE are unlikely to be affected by isospin violating interactions. In an
effective operator approach, we investigate conservative upper bounds on the
DM-quark couplings required by the IVDM scenario from the cosmic ray antiproton
fluxes measured recently by BESS-Polar II and PAMELA, and that from the relic
density. The results show that the relatively large couplings favored by DAMA
and CoGeNT are tightly constrained, if the operators contribute to
velocity-independent annihilation cross sections. For thermal relic DM, the
upper bounds from the relic density can also be stringent.
