From Pamela to CDMS and Back

Abstract

We take the recent result from the CDMS collaboration as a hint that the dark matter has an elastic scattering cross section with the nucleon in the vicinity of 10^-7 pb. By crossing symmetry such a cross section implies annihilation of dark matter into hadrons inside the halo, resulting in an anti-proton flux that could be constrained by data from the PAMELA collaboration if one includes a large boost factor necessary to explain the PAMELA excess in the positron fraction. As an illustration, we present a model-independent analysis for a fermionic dark matter and study the upper bound on the boost factor using the PAMELA anti-proton flux.

Figures (4)

• Figure 1: CDMS exclusion limit at 90% C.L. (the left axis) and the inferred DM annihilation into quarks without the boost factor (the right axis). For proof of concept, we assume a DM with cross section and mass coverage in the blue region below the present observed limit (blue solid line) and above the expected limit (blue dashed line). The plot assumes a heavy mediator case.
• Figure 2: The exclusion limits by the PAMELA anti-proton fraction at the 90% C. L. The red dashed line is the limit for DM annihilation into two quarks while the red dotted line is for annihilating into four quarks. Again the CDMS inferred annihilation rates are without the boost factor.
• Figure 3: The upper bound on the (effective) boost factor. The shaded region is disfavored.
• Figure 4: The spectra for the anti-proton fraction, assuming DM annihilation into two quark final states.