Strong CP problem
= Strong CP problem
{c}
{wiki}
The strong CP problem asks why the physical QCD theta angle is smaller than roughly $10^{-10}$ even though no Standard Model symmetry requires this small value.
= Strong CP problem
{c}
{wiki}
The strong CP problem asks why the physical QCD theta angle is smaller than roughly $10^{-10}$ even though no Standard Model symmetry requires this small value.