Why renormalizable theory is useful? I want to know detail reason for above question.
At a glance, I know following things.
In quantum field theory, $i.e$ computing self-energy(or self-interaction) Feynamn diagrams gives infinite divergence. This is un-physical. By removing this divergence, using renormalization scheme we can make infinite to finite quantity and obtain physical quantity.
Other famous example for infinite divergence is magnetic moment calculation in QED. This can be cured by renormalization also.
In a sense, i felt that renormalization procedure is nothing but a removing infinite divergence and make it finite. But i don't feel comfortable about this answer.
Can you give me more precise or reliable answer?