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Correlation functions near the critical point

1975; Institute of Physics; Volume: 8; Issue: 5 Linguagem: Inglês

10.1088/0305-4470/8/5/007

1361-6447

Franz Wegner,

Quantum, superfluid, helium dynamics

Using renormalization group arguments the author expands n-point correlation functions (for non-exceptional wavevectors) in expectation values of translational invariant short-range operators Oi. He uses the fact that the Fourier components of our operators become negligible for wavevectors q large in comparison to the momentum cut-off. The correlation functions show the same non-analyticities at the critical point as the expectation values (Oi). The expansion coefficients are regular in the thermodynamic variables for q not=0. They can be expressed in terms of (a) functions which become singular at q=0 and yield the scaling behaviour, and (b) functions which are regular at q=0. The expansion coefficients of the two-point correlation function are sums of both types of functions.