Abstract
We evaluate the impact of one-loop electroweak corrections to the spin-independent dark matter (DM) scattering cross-section with nucleons (σSI), in models with a so-called blind spot for direct detection, where the leading-order prediction for the relevant DM coupling to the Higgs boson, and therefore σSI, are vanishingly small. Adopting a simple illustrative scenario in which the DM state results from the mixing of electroweak singlet and doublet fermions, we compute the relevant higher order corrections to the scalar effective operator contributions to σSI, stemming from both triangle and box diagrams involving the SM and dark sector fields. It is observed that in a significant region of the singlet-doublet model-space, the one-loop corrections “unblind” the tree-level blind spots and lead to detectable SI scattering rates at future multi-ton scale liquid Xenon experiments, with σSI reaching values up to a few times 10−47 cm2, for a weak scale DM with mathcal{O}(1) Yukawa couplings. Furthermore, we find that there always exists a new SI blind spot at the next-to-leading order, which is perturbatively shifted from the leading order one in the singlet-doublet mass parameters. For comparison, we also present the tree-level spin-dependent scattering cross-sections near the SI blind-spot region, that could lead to a larger signal. Our results can be mapped to the blind-spot scenario for bino-Higgsino DM in the MSSM, with other sfermions, the heavier Higgs boson, and the wino decoupled.
Highlights
A well-studied example of the above scenario where the one-loop contributions to the dark matter (DM)-nucleon scattering rate become important is DM belonging to a multiplet of the Standard Model (SM) weak interaction group SU(2)L [6, 7]
The contribution to the effective DM-quark interaction from the vertex corrections represented by the triangle diagrams in figure 1a, fNtri, has the same form as the tree-level t-channel Higgs exchange vertex, with the Higgs-DM coupling Ch0χ01χ01 replaced by its oneloop counterpart Chtrχi01χ01
Such small leading order rates are obtained generically in dark matter models where the DM state results from the mixing of electroweak singlet and doublet states, due to cancellations in DM coupling to the Higgs boson, which is the primary mediator of SI interactions for Majorana fermion WIMPs
Summary
The mixing between the singlet and the neutral components of the doublet states occurs after electroweak symmetry breaking. Such a scenario can appear in beyond-the-standardmodel constructions such as the MSSM, in which the singlet state is the bino, and the two doublet states correspond to the two Higgsinos. The lightest neutral state in the dark sector is the DM candidate, where the mass spectrum and Yukawa couplings of the dark sector particles are determined by the following Lagrangian. The neutral components of the doublet and singlet dark fermions mix, and the mass matrix of neutral dark sector in the gauge basis χ0 = (χS, −χ02, χ01) is given by MS.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
