DM Exclusion Plots: Investigating WIMP Mass & Cross Section Relations

[tryhard]

I have been working hard to get the Dark Matter exclusion plots.

In most of the papers (arxiv:0808.3607), I found that the relation betweem WIMP mass and WIMP cross section is :

σ is directly proportional to (μ/μp)^2

σ=cross section
μ=reduced mass of WIMP and target nucleus
μp=reduced mass of WIMP and proton.

This clearly gives a monotonically increasing function, which is unlike the DM exclusion plot, which decreases to some value and then increases. Where am I going wrong ??

 

[mfb]

Exclusion plots are directly targeted at the cross-section - they don't depend on theory predictions for this value. For exclusion plots from experiments, you have to consider the detector sensitivity. Different WIMP masses lead to different energy depositions in the detector, and larger values are easier to detect. On the other hand, the predicted WIMP flux (to relate event rates with a cross-section) depends on the mass of the particle.