Probing multicomponent FIMP scenarios with gamma-ray telescopes

Abstract

We consider a scenario where the dark sector includes two Feebly Interacting Massive Particles (FIMPs), with couplings to the Standard Model particles that allow their production in the Early Universe via thermal freeze-in. These couplings generically lead to the decay of the heavier dark matter component into the lighter, possibly leading to observable signals of the otherwise elusive FIMPs. Concretely, we argue that the loop induced decay ψ 2 → ψ 1 γ for fermionic FIMPs, or φ 2 → φ 1 γγ for scalar FIMPs, could have detectable rates for model parameters compatible with the observed dark matter abundance.

Scalar and fermion two-component SIMP dark matter with an accidental ℤ4 symmetry

“…It follows that the freeze-out temperature of DM is T f m X /20 O(1) MeV, thereby the relativistic degrees of freedom in the thermal plasma the DM particles mainly interact with are electron and positron. 8 Accordingly, we then consider the following Lagrangian based on eq. (2.20) for the thermalization of the DM and e ± as…”

“…As we have discussed in this section, a sufficiently large dark gauge coupling is required to maintain the kinetic equilibrium between the DM and SM particles. There are a couple of factors that make the R N N →X are suppressed by the two-loop factor (4π) 8 . Firstly, we have to choose strong couplings, λ 3 y N ∼ O (10), to satisfy the relic abundance of DM.…”

“…Thirdly, the mass of Z in the tree-level graphs is heavier than that of S in the two-loop diagrams, where m Z ∼ 4m S . As a result, the R N N →X X , for instance, is roughly equal to (4π) 8…”

“…Lastly, there is a possibility that the universe contains more than one kind of DM just like the visible world exist many stable particles such as the electron, proton, and neutrinos. Indeed, there are many efforts along this direction [2][3][4][5][6][7][8][9][10].…”

Freezing In with lepton flavored fermions

“…As can be seen, a significant region of the parameter space is already ruled out from XENON1T data with LZ and DARWIN projected to probe a much larger region of this model. There exist FIMP models that derive constraints from indirect detection experiments [14,100], CMB and astrophysics experiments [48,50,[101][102][103][104], and at colliders [105,106]. However, we estimate that these constraints do not probe the models studied in this work [107][108][109][110][111].…”