What does this equation mean?

Here each $\mathcal{O}_i^{(6)}$ is a dimension-six operator built from Standard Model fields respecting its gauge symmetries, and $c_i$ is a dimensionless Wilson coefficient encoding the strength and structure of whatever heavy new physics generated it. This is not a discovery claim; it is a bookkeeping device, and its value is precisely that it is agnostic about what the new physics is. A single measured deviation — in a Higgs coupling, in a rare decay rate, in an electroweak precision observable — constrains a combination of these coefficients without committing to SUSY, extra dimensions, or any other specific completion. The framework became central exactly because two decades of direct searches had not handed theorists a specific particle to build a model around; EFT lets the data itself outline the shape of whatever is missing, before anyone commits to a story about what fills that shape in. It is a methodological shift as much as a theoretical one, and it is fair to call it the field’s dominant working language today, alongside — not replacing — continued direct searches for specific particles.