Perturbation, chiral time-dependent

The contribution of the hadronic l-l scattering effect (32) is relatively small but is potentially a source of serious problem because it is difficult to express in terms of experimentally accessible observables it must be evaluated by theoretical consideration. It has been estimated by two groups, within the framework of chiral perturbation theory and the 1 /Nc expansion [64,65], Recently the theory dependence of these calculations has been reduced [31] by improving a part of the calculation incorporating the measurements of the P77 form factors [66], where P stands for 7r°, 77, and rj. The value quoted in (32) is the result of this work. Evaluation of these effects in lattice QCD will be particularly timely and interesting. 

The idea that the vacuum represents an achiral interface that separates two space-time segments of opposite chirality developed from the notion that mass-dependent quantum effects arise from a field in the vacuum which affects the smallest of objects most prominently. The original argument (Boeyens, 1992) was that quantum behaviour results from feeble interactions through the interface, which create the impression of random wave-like perturbations imposed on the regular motion of small particles. 

---