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.