Light dark matter from leptogenesis

Abstract

We consider the implications of a shared production mechanism between the baryon asymmetry of the universe and the relic abundance of dark matter, that does not result in matching asymmetries. We present a simple model within a two sector leptogenesis framework, in which right handed sterile neutrinos decay out of equilibrium to both the Standard Model and the dark sector, generating an asymmetry in one and populating the other. This realization naturally accommodates light dark matter in the keV mass scale and above. Interactions in the dark sector may or may not cause the sector to thermalize, leading to interesting phenomenological implications, including hot, warm or cold thermal relic dark matter, while evading cosmological constraints. Under minimal assumptions the model provides a novel non-thermal production mechanism for sterile neutrino dark matter and predicts indirect detection signatures which may address the unexplained 3.5 keV line observed in various galaxy clusters.

UV freeze-in in Starobinsky inflation

“…Although the scenario presented here assumes a trivial dark sector dynamics, it is conceivable that it could display sufficiently strong interactions leading to self-thermalization. This could have a strong impact on the DM abundance, opening the possibility of having a dark freeze-out in the dark sector [59][60][61][62][63][64][65]. In particular, if the dark sector could thermalize within itself, its entropy would be conserved instead of its number density, leading to an additional enhancement of the DM abundance [66].…”

“…Thermalization and number-changing processes within the dark sector can have a strong impact on the DM relic abundance. In particular, they can enhance the DM abundance by several orders of magnitude[59][60][61][62][63][64][65][66] 12. We restrict ourselves to perturbative production of DM below the scalaron mass M , acknowledging the potential production of super heavy candidates via non-perturbative processes[68].…”

Stealth decaying spin-1 dark matter

“…In order to estimate the resulting bound on the VDM parameter space, we follow ref. [16] and simply demand that the VDM free-streaming scale does not exceed 0.1 Mpc. 6 In the radiation-dominated era, the DM free-streaming scale is [75] λ FS ≈ a NR H 0 √ Ω R 0.62 + log a eq a NR , (4.7)…”

“…Consequently, the relic abundance only depends on DM properties that can be probed in experiments. Also, FIMP may be related to leptogenesis [16].…”

Accretion of dissipative dark matter onto active galactic nuclei

“…The situation has changed in recent years. With the lack of experimental evidence for DM or for a solution to the hierarchy problem, light DM residing in a low-scale "dark sector" has attracted significant attention [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The low, sub-GeV, mass scale arises both theoretically and observationally: from the theoretical viewpoint, many production mechanisms that explain the observed relic abundance, require DM to have a low mass and possibly to interact strongly within the dark sector (see, e.g., [19][20][21][22][23][24][25][26][27][28][29][30]); from the observational perspective, several discrepancies with N-body simulations suggest that DM may have rather strong self-interactions [31][32][33][34].…”