Constraining the interaction strength between dark matter and visible matter: I. Fermionic dark matter

In this work we study the constraints on the dark matter interaction with the standard model particles, from the observations of dark matter relic density, the direct detection experiments of CDMS and XENON, and the indirect detection of the p¯/p ratio by PAMELA. A model independent way is adopted in the study by constructing the effective interaction operators between dark matter and standard model particles. The most general 4-fermion operators are investigated. We find that the constraints from different observations are complementary with each other. Especially the spin independent scattering gives very strong constraints for corresponding operators. In some cases the indirect detection of p¯/p data can actually be more sensitive than the direct detection or relic density for light dark matter (≲70 GeV≲70 GeV).