Hi, I'm reading an article called SuperSymmetric Dark Matter, by G. Jungman et al. doi:10.1016/0370-1573(95)00058-5 and in section 3.2, he claims that(adsbygoogle = window.adsbygoogle || []).push({});

[itex]<σv> ≈ \alpha^{2}(100 GeV)^{-2} \approx10^{-25} cm^{3} s^{-1},[\itex] for [itex]\alpha \approx \frac{1}{100}.[/itex]

When I run through the calculation, I get 1x10[itex]^{-29}[/itex]. Have I tripped up in my calculation or am I missing an assumption somewhere?

my calculation:

[itex]\frac{0.01^{2}}{10^{4}GeV^{2}} = 1GeV^{-2}= 1GeV^{-2}(\hbar c)^{2}c = 3\times10^8\times4\times10^{-2}fm^{2}ms^{-1}=1\times10^{7}\times(\frac{1m}{10^{15}fm})^{2}ms^{-1}fm^{2} = 1\times10^{7}\times10^{-30}m^{3}s^{-1} = 1\times10^{-29}cm^{3}s^{-1}[/itex]

Also he claims that his value for Ωh[itex]^2 \approx 3\times10^{-2}[/itex] is close to the value measured [itex]\approx 0.22[/itex] but it is a full order of magnitude off...

I know that a portion of cold dark matter is in machos and in baryonic matter but that cannot account for the discrepancy between the measured value and Jungman's predicted value. Can anybody help me understand?

Thanks, Dan

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# WIMP annihilation cross section

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