Equation 4 · Part 7 · How Particle Physics Beyond the Standard Model Actually Works

=

\mathcal{L}_{\text{eff}} = \mathcal{L}_{\text{SM}} + \sum_i \frac{c_i}{\Lambda^{2}}\,\mathcal{O}_i

What this part means

The expressions on both sides represent the same quantity under the stated assumptions.

Its job in the formula

The equals sign connects the complete expression on the left with the complete expression on the right. Both sides must have compatible units.

Full expression=Article meaning

The passage around this formula

If a new particle is too heavy to produce directly, its effects can still appear as small deviations in the interactions of known particles, encoded as additional terms in an effective Lagrangian: $\mathcal{L}_{\text{eff}} = \mathcal{L}_{\text{SM}} + \sum_i \frac{c_i}{\Lambda^{2}}\,\mathcal{O}_i$ . Here $\mathcal{O}_i$ are Standard-Model-field operators of dimension six, $c_i$ are unknown coefficients, and $\Lambda$ is the mass scale of whatever new physics has been integrated out. This is the Standard Model Effective Field Theory (SMEFT) framework used across current LHC and dark-matter searches. Its value is precise and limited: it lets an experiment quote a model-independent bound on $c_i$ / $\Lambda^2$ from a measured deviation (or non-deviation) without committing to what…

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Learn the underlying idea

An equals sign says that the expression on its left and the expression on its right have the same value under the stated definitions and assumptions.

Open the illustrated equality: what the equals sign claims guide →

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