Why in two dimension space many QTFtheory become renormalizable?

[ndung200790]

Please teach me this:
Why in two dimension space many QTF theories become renormalizable.By the way,are there any relation between this and the world-sheet in string theory?
Thank you very much in advance

 

[matonski]

Because loops now go as $\int d^2 p$ while propagators still go as $p^2$