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7 Conclusions

[1289.3.1] Two fractional relaxation models (model A and model B) were shown to fit broad band dielectric spectroscopy data for various glass forming materials. [1289.3.2] For 5-methyl-2-hexanol and methyl-m-toluate the 3-parameter model A can fit data over a range of 6 and 7 orders of magnitude. [1289.3.3] Generally we observed good fits over a range of at least 5 orders of magnitude for model A and 10 orders of magnitude for model B. [1289.3.4] Conventional fitting formulae (such as Havriliak-Negami and Cole-Cole) require 6 parameters in contrast to 3 for model A resp. 4 for model B. [1289.3.5] In summary, this work has given closed form analytical expressions for excess wings containing only three (or four) parameters, that are derived from the previously introduced method of composite fractional time evolutions [17, 18] and are directly applicable to experiment.