QCD and String Theory

Few natural basic principles allow to extend Feynman integral over the paths to an integral over the surfaces so, that they coincide at long time scale, that is when the surface degenerates into a single particle world line. In the classical approximation the loop Green functions have perimeter behavior. That corresponds to the free quarks. Quantum fluctuations of the surface generate nonzero string tension, that is the area law and we have quark confinement. In this string theory confinement and asymptotic freedom can coexist.