Speaker
Description
The traditional tools to calculate the relic abundance of dark matter (DM) typically solve the Boltzmann equation at an integrated level---reducing the evolution of the phase space density to that of the number density---and in doing so are crucially reliant upon the assumption of chemical decoupling of DM preceding its kinetic decoupling from the Standard Model heat bath. However, this condition is known to be violated in well-motivated physics scenarios, for e.g. with resonant annihilation. The Mathematica based code DRAKE was developed to enable the computation of the time evolution of a (single component) DM phase-space density, or its lowest moments, and to thereby obtain the DM relic abundance produced outside of kinetic equilibrium. In full generality, the dark sector can be comprised of multiple particles, one or more of which can make up the total observed DM abundance. In such scenarios, the existence of multiple number changing processes (for example within the dark sector) further challenges the assumption of kinetic equilibrium of DM during freeze-out, and thereby poses challenges to the standard relic abundance calculation. In this short talk, I will present the developments in the code DRAKE as a tool for calculating the evolution of the phase space densities of two coupled, dark state particles, in scenarios where their kinetic equilibrium cannot be guaranteed apriori. As an example of the implementation of this extended version of DRAKE for 2 component dark sector, I will briefly present results from representative phenomenological studies where we find that departure from kinetic equilibrium can alter the predictions for the total DM abundance from O(10%) to more than 100%.
