Strong CP problem

Strong CP problem: why does QCD not violate CP symmetry?

Quantum chromodynamics (QCD) theoretically allows for CP-symmetry violation in strong interactions, yet experiments show no such violation.

The strong CP problem arises because QCD does not have a known reason to conserve CP-symmetry, leading to a fine-tuning issue in particle physics.

Several solutions, including the Peccei–Quinn theory with axions, have been proposed to address this unsolved puzzle.

Example

No experimental evidence of CP-symmetry violation in strong interactions despite QCD's theoretical allowance.

Remember this

Understanding the strong CP problem is crucial for advancing theoretical physics and achieving a unified understanding of fundamental forces.

Text adapted from Wikipedia, licensed under CC BY-SA 4.0.

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