The electromagnetic force of quarks

[MacGyver Megh]

TL;DR Summary

Why there is strong force while quarks has charge themselves?

If an up quark has 2/3 of positive charge and down quark has 1/3 of negative charge then why don't they add together by their electromagnetic force?

 

[Orodruin]

There are several observational facts that mean that electromagnetism is not enough.

To start with, electromagnetism is not strong enough to bind two quarks of opposite charge as tightly as a nucleus or a meson. Instead, you would get something of a size similar to an atom, which is about five orders of magnitude larger.

Second, electromagnetism could not produce a proton, which has a net positive charge. Instead of being an energetically favoured state, the proton would not constitute a bound state and we would not exist.

Third, electromagnetism cannot explain several other effects that has to do with quarks, such as the color factor appearing in meson production and similar things.

 

[mfb]

To add some more problems:
It would allow 1 up and 1 down to combine to a stable particle - but we don't see that in nature.
It would allow individual quarks to be free - but we don't see that in nature.
It would not allow the existence of $\Delta^{++}$ made out of three up quarks or $\Delta^-$ made out of three down quarks - but we found these particles.
It would not allow the existence of larger nuclei - but we see them in nature.

 

[MacGyver Megh]

Could you please tell me why electromagnetism is not enough? And what sort of observations they had been faced?

 

[Orodruin]

Could you please tell me why electromagnetism is not enough?

I already told you that:

Instead, you would get something of a size similar to an atom, which is about five orders of magnitude larger.

 

[MacGyver Megh]

I already told you that:

Can you please give an example or the equations what is five time larger magnitudes?

 

[Orodruin]

Can you please give an example or the equations what is five time larger magnitudes?

It means that the radius of the nucleus would be around $10^5 = 100000$ times larger than what is observed.