Mode coupling theory , background

The decay rate (first cumulant) T of the time-dependent correlation function associated with the order parameter fluctuations can be measured by dynamic light scattering. Mode-coupling theories of critical phenomena including dynamical background contributions predict that is the sum of a critical part Tf and a background part Tb, i.e.. 

Because several other chapters in this volume require a certain background in the use of projection operators, it was felt that this chapter should provide some of this background. In particular, Chapter 6 on mode-mode coupling theory by Keyes and Chapter 4 on modern kinetic theory by Mazenko and Yip use some of the basic notions presented here. Thus we are constrained somewhat in our choice of topics. Nevertheless, some effort will be made to indicate simple applications of this technique. 

In analogy with equation (6.19) each of the coefficients introduced in equations (6.43) and (6.44) is written as a sum of a regular background contribution and a critical enhancement, that is, a = a -f- Aofc. etc. Since the mode-coupling theory provides information... 

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