# What happens if up quarks are replaced by down quarks and down quarks are replaced by up quarks?

I believe the quarks would flip the proton's internal charge, reverse the spin of the proton, transform into another flavor, and then become unconfined and free.

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The proton ($uud$) turns into a neutron ($ddu$). Up and down quarks don't have equal charges; the up is $+\frac{2}{3}e$ and the down is $-\frac{1}{3}e$.

By the way, such an operation has a name - isospin symmetry transformation - corresponding to an approximate SU(2) symmetry that makes the proton and neutron have almost similar masses.

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Um... no, there's no reason to think any of that stuff would happen. The transformation of up quarks into down quarks and vice versa is called an isospin transformation, and it's been quite well studied. For example, the proton and neutron are members of an isospin doublet, which means that making this transformation would convert each one into the other.

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Thanks for the assistance, guys. I really understand the grounds on how this community functions on now. –  user3322 Apr 28 '11 at 8:03