Analytic calculation of the anomalous exponents in turbulence: Using the fusion rules to flush out a small parameter

The main difficulty of statistical theories of fluid turbulence is the lack of an obvious small parameter. In this paper we show that the formerly est ablished fusion rules can be employed to develop a theory in which Kolmogor ov's statistics of 1941 (K41) acts as the zero order, or background statist ics, and the anomalous corrections to the K41 scaling exponents xi (n) of t he nth-order structure functions can be computed analytically. The crux of the method consists of renormalizing a four-point interaction amplitude on the basis of the fusion rules. This amplitude includes a small dimensionles s parameter, which is shown to be of the order of the anomaly of xi (2), de lta (2)=xi (2) - 2/3 approximate to0.03 Higher-order interaction amplitudes an shown to be even smaller. The corrections to K41 to 0(delta (2)) result from standard logarithmically divergent ladder diagrams in which the four- point interaction acts as a "rung." The theory allows a calculation of the anomalous exponents xi (n) in powers of the small parameter delta (2). The n dependence of the scaling exponents xi (n) stems from pure combinatorics of the ladder diagrams. In this paper we calculate the exponents xi (n) up to 0(delta (3)(2)). Previously derived bridge relations allow a calculation of the anomalous exponents of correlations of the dissipation field and of dynamical correlations in terms of the same parameter delta (2). The actua l evaluation of the small parameter delta (2) from first principles require s additional developments that are outside the scope of this paper.