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Equation 3 · Part 2 · How Particle Physics Beyond the Standard Model Actually Works

subscript

θ13\theta_{13}
subscript

What this part means

The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.

Its job in the formula

A subscript distinguishes a version, component, step, or member of a quantity. It does not automatically mean multiplication.

The passage around this formula

What an experiment like T2K or NOvA reports is not a discovery of new particles but a set of numbers: mixing angles ( θ12\theta_{12} , θ23\theta_{23} , θ13\theta_{13} ) and the mass-squared differences between neutrino mass states, extracted from how oscillation probability varies with neutrino energy over a fixed baseline. A joint 2024 analysis combining a decade of T2K data with six years of NOvA data pushed the precision on one mass-squared splitting below 2%, but — and this is the honest state of the field, not a caveat — it did not resolve whether the neutrino mass ordering is “normal” or “inverted,” and left the CP-violating phase (a potential source of the matter-antimatter asymmetry)…

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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 →

Sources cited in the surrounding passage

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