sub-GeV dark matter relic abundance not accurate

[Taylor Gray]

I'm not sure if there is a fix on my end for this or if this is only for certain models, but I notice for sub-GeV mass dark matter (precisely 1 MeV - 1 GeV) the relic abundance calculations in madDM are not accurate. This occurred for a scalar and a vector DM model.
There seems to be similar issues with madgraph at small masses as well (for example, I noticed this when computing dark photon Bremsstrahlung in madgraph).

[Chiara Arina (carina)]

Hi,

can you tells us more precisely what you mean with the fact that the relic abundance for sub-GeV dark matter is not accurate? There are theoretical issue for the regime of sub-GeV dark matter, such as the parametrisation of the QCD scale, decoupling of light particles, kinetic equilibrium, that can change the results. All the theoretical issues are not considered in MadDM which has been designed for GeV and above dark matter. So the results for light particles should be taken with caution. Besides the theoretical issues, we are not aware of numerical problems: if the latter are what you mean, that would be helpful if you could clarify your query.
Similarly for madgraph, it would be helpful if you could provide more infos about what you are looking for and what is the problem with the results you have obtained.

Thanks

Chiara