What does this equation mean?

where each $\mathcal{O}_i^{(6)}$ is a dimension-six operator built from Standard Model fields and $c_i$ is a dimensionless Wilson coefficient set by the details of the underlying theory. This notation is worth showing because it makes the comparison’s real structure explicit: SUSY, extra dimensions, and dark-sector models are each, in this language, a specific choice of which $\mathcal{O}_i$ operators get generated and with what coefficients. A null search in a global SMEFT fit constrains $c_i$/$\Lambda^2$ combinations directly from precision electroweak, Higgs, and flavor data, without committing to which particle content produced them [ 7 ] . The tradeoff is exactly the one implied by that generality: an EFT fit can tell you that new physics coupling to a particular operator must lie above some energy scale, but it cannot, by itself, tell you whether that new physics looks like a superpartner, a Kaluza-Klein mode, or a dark-sector mediator. It is the most model-independent of the four approaches and, for that reason, the hardest to describe as “confirmed” or “excluded” in the way a direct search can be.