Fully Geant4 compatible package for the simulation of Dark Matter in fixed target experiments

Abstract

We present the package for the simulation of DM (Dark Matter) particles in fixed target experiments. The most convenient way of this simulation (and the only possible way in the case of beam-dump) is to simulate it in the framework of the Monte-Carlo program performing the particle tracing in the experimental setup. The Geant4 toolkit framework was chosen as the most popular and versatile solution nowadays.Specifically, the package includes the codes for the simulation of the processes of DM particles production via electron and muon bremsstrahlung off nuclei, resonant in-flight positron annihilation on atomic electrons and gamma to ALP (axion-like particles) conversion on nuclei. Four types of DM mediator particles are considered: vector, scalar, pseudoscalar and axial vector. The total cross sections of bremsstrahlung processes are calculated numerically at exact tree level (ETL).The code handles both the case of invisible DM decay and of visible decay into e+e− (μ+μ− for Z′, γγ for ALP).The proposed extension implements native Geant4 application programming interfaces (API) designed for these needs and can be unobtrusively embedded into the existing applications.As an example of its usage, we discuss the results obtained from the simulation of a typical active beam-dump experiment. We consider 5×1012 100 GeV electrons impinging on a lead/plastic heterogeneous calorimeter playing a role of an active thick target. The expected sensitivity of the experiment to the four types of DM mediator particles mentioned above is then derived. Program summaryProgram Title: DMG4CPC Library link to program files:https://doi.org/10.17632/6m3yhx4ssw.1Licensing provisions: GNU General Public License 3Programming language: c++Nature of problem: The optimal way to simulate Dark Matter production processes in fixed target experiments in most cases is to do it inside the program for the full simulation of the experimental setup and not separately, in event generators. The code that can be easily embedded in such programs is needed. The code should be able to simulate various DM production processes that happen in a thick target, in particular on nuclei, with maximal accuracy.Solution method: We created a Geant4 compatible DM simulation package for this purpose. The choice of this simulation framework is suggested by its popularity and versatility. The code includes the cross sections precalculated at exact tree level for a wide variety of DM particles.