micrOMEGAs5.0 : freeze-in

TL;DR

This paper introduces an upgraded micrOMEGAs code capable of accurately computing dark matter abundance via the freeze-in mechanism, considering detailed phase-space distributions and various scenarios.

Contribution

The paper develops a formalism for freeze-in dark matter calculations and implements it in micrOMEGAs, enabling precise treatment of statistics and diverse models.

Findings

Proper statistical treatment can alter dark matter abundance predictions by up to a factor of two.

The upgraded code handles multiple freeze-in scenarios with minimal simplifying assumptions.

Example results demonstrate the code's capability across different dark matter models.

Abstract

We present a major upgrade of the micrOMEGAs dark matter code to compute the abundance of feebly interacting dark matter candidates through the freeze-in mechanism in generic extensions of the Standard Model of particle physics. We develop the necessary formalism in order to solve the freeze-in Boltzmann equations while making as few simplifying assumptions as possible concerning the phase-space distributions of the particles involved in the dark matter production process. We further show that this formalism allows us to treat different freeze-in scenarios and discuss the way it is implemented in the code. We find that, depending on the New Physics scenario under consideration, the effect of a proper treatment of statistics on the predicted dark matter abundance can range from a few percent up to a factor of two, or more. We moreover illustrate the underlying physics, as well as the various novel functionalities of micrOMEGAs, by presenting several example results obtained for different dark matter models.