# The Standard Model's loose ends

- kind: region

The best-tested theory in science, with a list of numbers it cannot explain and particles it does not include.

## Problems

- [The Higgs boson](/wiki/Problem:higgs-boson.md) (solved)
- [The hierarchy problem](/wiki/Problem:hierarchy-problem.md) (open)
- [The strong CP problem](/wiki/Problem:strong-cp.md) (open)
- [Neutrino masses](/wiki/Problem:neutrino-mass.md) (partial)
- [Yang–Mills existence and mass gap](/wiki/Problem:yang-mills-mass-gap.md) (open)

Part of [Physics](/wiki/Continent:physics.md).

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