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 ??