Sterile neutrino portals to Majorana dark matter: effective operators and UV completions

Abstract

Stringent constraints on the interactions of dark matter with the Standard Model suggest that dark matter does not take part in gauge interactions. In this regard, the possibility of communicating between the visible and dark sectors via gauge singlets seems rather natural. We consider a framework where the dark matter talks to the Standard Model through its coupling to sterile neutrinos, which generate active neutrino masses. We focus on the case of Majorana dark matter, with its relic abundance set by thermal freeze-out through annihilations into sterile neutrinos. We use an effective field theory approach to study the possible sterile neutrino portals to dark matter. We find that both lepton-number-conserving and lepton-number-violating operators are possible, yielding an interesting connection with the Dirac/Majorana character of active neutrinos. In a second step, we open the different operators and outline the possible renormalisable models. We analyse the phenomenology of the most promising ones, including a particular case in which the Majorana mass of the sterile neutrinos is generated radiatively.

Asymmetries in Extended Dark Sectors: A Cogenesis Scenario

“…Finally, let us remark that the necessary ingredients for the model to work could also be achieved with a global U (1) B−L [16,44], explicitly violated by right-handed neutrino masses, since: i) χ is Dirac in nature because of the gauge U (1) D , ii) it has sizeable interactions with the SM (with N R , y S ) to thermalise, and iii) it can undergo efficient annihilations due to the U (1) D gauge group.…”

“…Several extensions of the SM have been proposed, where either a single particle or several stable particles, i.e., multi-component DM [1][2][3][4][5][6][7][8][9], make up the observed DM relic abundance, Ω DM h 2 ∼ 0.1 [10]. The most popular mechanisms to reproduce this relic abundance include thermal freeze-out (FO) of weakly interacting massive particles (WIMPs) [11][12][13][14][15][16] and freeze-in (FI) of feebly interacting massive particles (FIMPs) [17][18][19].…”