# What decides electric charge of a particle? how do particles create their own electromagnetic field?

What decides electric charge of a particle? A proton has 3 quarks (up,up,down) we know that according to charge of those quarks decides the charge of proton but what decides charge of those quarks? not only quarks every particles in standard model? how do they create their own electromagnetic field? what creates their field?

• Related: physics.stackexchange.com/q/31247/2451 , physics.stackexchange.com/q/33990/2451 and links therein. Jan 7 '17 at 18:28
• It's their coupling to the electromagnetic field that decides the charge. For example an electron has a term proportional to $e A_\mu$ in its Lagrangian where $e$ is the charge and $A_\mu$ is the electromagnetic field. Jan 7 '17 at 18:29