Quantum-classical crossover in quasi-one-dimensional systems

New results are obtained for quasi-one-dimensional systems. Quantum fluctuations are treated by the Wilson renormalization group and are shown to have a strong influence on the three-dimensional correlations for systems with two-particle interchain coupling. The nonuniversal character of the quantum-classical crossover and the implications on the standard microscopic Ginzburg-Landau theory are examined. We also point out a possible connection to the experimental results on the ${\mathrm{}\left(\mathrm{tetramethyltetrathiafulvalenium}\right)\mathrm{}}_2-X[{\mathrm{}\left(\mathrm{TMTSF}\right)\mathrm{}}_2-X]$ compounds.