Equation 2 · Part 4 · Comparing the Main Approaches to Particle Physics Beyond the Standard Model

Symbol c_i

\mathcal{L}_{\text{SMEFT}} = \mathcal{L}_{\text{SM}} + \sum_i \frac{c_i}{\Lambda^{2}} \mathcal{O}_i^{(6)} + \mathcal{O}\!\left(\frac{1}{\Lambda^{4}}\right)

c_i

What this part means

a dimensionless Wilson coefficient set by the details of the underlying theory.

Its job in the formula

$c_i$ occurs above the fraction bar. The numerator is divided by the entire denominator below it.

Full expressionSymbol c_iArticle meaning

Where the article explains it

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.

The passage around this formula

…by powers of an energy scale $\Lambda$ representing the mass of whatever new particles generate it: $\mathcal{L}_{\text{SMEFT}} = \mathcal{L}_{\text{SM}} + \sum_i \frac{c_i}{\Lambda^{2}} \mathcal{O}_i^{(6)} + \mathcal{O}\!\left(\frac{1}{\Lambda^{4}}\right)$ . 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 $\mathcal{O}_i$ …

Read this part in the article →

Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

Open the illustrated subscripts: which member of a family? guide →

See this notation across published equations →

Sources cited in the surrounding passage

[7] The Standard Model effective field theory at work ↗

These citations provide research context; check each source for the exact claim it supports.