Implications of the latest XENON100 and cosmic ray antiproton data for isospin violating dark matter

Abstract

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.