Effective theory of WIMP dark matter supplemented by simplified models: Singlet-like Majorana fermion case

Abstract

We enumerate the set of simplified models which match onto the complete set of gauge invariant effective operators up to dimension six describing interactions of a singlet-like Majorana fermion dark matter with the standard model. Tree level matching conditions for each case are worked out in the large mediator mass limit, defining a one to one correspondence between the effective operator coefficients and the simplified model parameters for weakly interacting models. Utilizing such a mapping, we compute the dark matter annihilation rate in the early universe, as well as other low-energy observables like nuclear recoil rates using the effective operators, while the simplified models are used to compute the dark matter production rates at high energy colliders like LEP, LHC and future lepton colliders. Combining all relevant constraints with a profile likelihood analysis, we then discuss the currently allowed parameter regions and prospects for future searches in terms of the effective operator parameters, reducing the model dependence to a minimal level. In the parameter region where such a model-independent analysis is applicable, and leaving aside the special dark matter mass regions where the annihilation proceeds through an s-channel Z or Higgs boson pole, the current constraints allow effective operator suppression scales (Λ) of the order of a few hundred GeV for dark matter masses m χ > 20 GeV at 95% C.L., while the maximum allowed scale is around 3 TeV for m χ ∼ (1 TeV). An estimate of the future reach of ton-scale direct detection experiments and planned electron-positron colliders show that most of the remaining regions can be probed, apart from dark matter masses near half of the Z-boson mass (with 500 GeV < Λ < 2 TeV) and those beyond the kinematic reach of the future lepton colliders.

Simplified models for dark matter face their consistent completions

“…The complementarity of different DM search avenues plays a very important role in the exploration of DM properties, and thus approaches which allow to fully exploit such complementarity have received a great deal of attention [3][4][5][6][7][8]. The leading two such approaches are effective field theories (EFTs) and DM simplified models.…”

Pseudo-Nambu-Goldstone dark matter: Examples of vanishing direct detection cross section

“…Thus, we postpone such analysis for the future. 9 Beyond the tree-level approximation So far, we have considered the direct detection cross section at the tree-level, which vanishes because of the PNGB nature of the DM particles, i.e. the approximate imposed symmetry.…”

“…Interesting possibilities include those that do not follow standard DM annihilation to SM particles and alter the way the DM freezes-out, 1 for example "secluded" [3,4] and "cannibal" [5] DM models. Other possibilities include suppression of the interaction between DM and the nucleons due to a heavy (integrated-out) mediator [6][7][8][9][10][11], the appearance of "blind spots" [12][13][14] or the smallness of the DM mass [15][16][17][18][19][20][21] (including in some cases "frozen-in" DM [22]) which makes the DM particle inaccessible to such experiments. 2 Among particularly appealing scenarios, however, direct detection experiments are unable to detect the WIMP due to symmetry arguments [30][31][32][33][34].…”

GAMBIT and its application in the search for physics Beyond the Standard Model

“…Prior to 2017, most global fits were focussed on supersymmetric theories, involving dedicated software that was built from the ground up with a knowledge of the supersymmetric parameters . These results typically covered low-dimensional subsets of the minimal supersymmetric SM (MSSM) or, in some cases the next-to-minimal variant, with relatively few global studies of other theories completed [96][97][98][99][100][101][102][103][104][105][106][107][108][109].…”