Dark matter freeze-in produces large post-inflationary isocurvature

Dark Matter from freeze-in and its inhomogeneities

“…the model considered in [7] DM has a small electric charge and is thereby produced by IRdominated scatterings of two SM particles, such as e − e + → DM DM. This generates, at any given time, a contribution to the DM density ρ DM proportional to the square of the SM density ρ SM , and DM inhomogeneities might be not proportional to SM inhomogeneities.…”

“…Weinberg answered positively this issue for thermal freeze-out: since freeze-out dominantly happens in the non-relativistic regime, computing inhomogeneities in the DM number density was enough [6]. On the other hand, freeze-in can be relativistic, and the iso-curvature issue started being considered recently: [7] claims that a specific freeze-in model is excluded because it generates too large scale-independent iso-curvature perturbations. The authors of [7] argue that all freeze-in models are similarly problematic.…”

“…On the other hand, freeze-in can be relativistic, and the iso-curvature issue started being considered recently: [7] claims that a specific freeze-in model is excluded because it generates too large scale-independent iso-curvature perturbations. The authors of [7] argue that all freeze-in models are similarly problematic. In…”

Freeze-in dark matter perturbations are adiabatic

“…CMB observations from the Planck collaboration [3] set stringent constraints on the amount of isocurvature fluctuations present on large-scales. A recent study [4] has claimed that too large isocurvature perturbations in the DM component are generated in the socalled freeze-in production mechanism [5][6][7], when DM particles are generated and never reach chemical equilibrium. If true, the freeze-in mechanism would be ruled out as a production mechanism for the totality of DM.…”

Data-Driven Insights to Cosmology in the Dark Universe

“…The particle-filtering analysis treated primary data as node points in the nucleon heuristics on superconductivity, and the plasma recombination was effective in the Kerr-Newman black hole type on NGC 3034 [20][21][22]. Weinberg theorized the possibility of proton decay only with the admission of extremely heavy exotic particles , and used a "freeze-in" method on the weakly-interacting massive particle within the BB nucleosynthesis constraints, resulting in perturbative isocurvature [5,23]. For non-perturbative observation in strong force CP violation, an axiomatic 0 charge separation is required and nearly impossible to achieve in heavy-ion collision experiments [19,24,25].…”