Abstract
We consider an effective field theory for a gauge singlet Dirac dark matter particle interacting with the standard model fields via effective operators suppressed by the scale Λ ≳ 1 TeV. We perform a systematic analysis of the leading loop contributions to spin-independent Dirac dark matter-nucleon scattering using renormalization group evolution between Λ and the low-energy scale probed by direct detection experiments. We find that electroweak interactions induce operator mixings such that operators that are naively velocity suppressed and spin dependent can actually contribute to spin-independent scattering. This allows us to put novel constraints on Wilson coefficients that were so far poorly bounded by direct detection. Constraints from current searches are already significantly stronger than LHC bounds, and will improve in the near future. Interestingly, the loop contribution we find is isospin violating even if the underlying theory is isospin conserving.
Highlights
We consider an effective field theory for a gauge singlet Dirac dark matter particle interacting with the standard model fields via effective operators suppressed by the scale Λ ≳ 1 TeV
In this Letter we consider the case of a standard model (SM) gauge singlet Dirac dark matter (DM) (χ), with mχ < Λ, and we calculate the complete set of one-loop effects induced by SM fields for operators up to dimension 6 that contribute to spin-independent (SI) DM–nucleon scattering
This procedure requires as a first step the computation of both electroweak (EW) and QCD running from the scale Λ to the EW symmetry breaking scale where threshold corrections are calculated and the heavy SM fields (Higgs boson, top quark, W and Z bosons) get integrated out, giving rise to new operators
Summary
We consider an effective field theory for a gauge singlet Dirac dark matter particle interacting with the standard model fields via effective operators suppressed by the scale Λ ≳ 1 TeV. The separation between Λ and the DD scale is systematically taken into account via a proper renormalization group (RG) analysis This procedure requires as a first step the computation of both electroweak (EW) and QCD running from the scale Λ to the EW symmetry breaking scale where threshold corrections are calculated and the heavy SM fields (Higgs boson, top quark, W and Z bosons) get integrated out, giving rise to new operators. The Higgs operator OSHH gives rise to OSqSq after EW symmetry breaking, and upon integrating out the heavy quarks the dimension-7 interaction with the gluon field strength OSgg is generated. This leads to the following threshold corrections: CSgg. whose form shows that the OSqSq contribution induced by tree-level Higgs exchange is enhanced since it scales like 1=ðΛm2h0Þ instead of 1=Λ3.
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