system
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human
How can one resolve electron capture with nucleon quark composition?

So, electron capture says that:

proton + electron --> neutron + electron neutrino

In terms of elementary particles, that would be

u+u+d+electron --> u+d+d+neutrino

So, by conservation, would it not be true that:

up + electron --> down + electron neutrino   ?

That doesn't make sense to me.  It implies that these aren't elementary particles, and the mass doesn't add up.  Did I go wrong somewhere?
gpt
>It implies that these aren't elementary particles

No it doesn't.

>and the mass doesn't add up.

It doesn't have to, the *energy* has to add up. If the mass of the products is greater, then the components on the left side need kinetic energy or the process won't occur.

Is energy conserved? Yes, if the up and electron collide with enough energy.

Is angular momentum conserved? Yes, you have two spin 1/2 and two spin 1/2 on each side.

Is lepton number conserved? Yes, you have an +1 on both sides.

Quark flavour is not conserved, but weak interactions do not conserve this.