· = < 01 (1 + -+ + + 2v)Z . (20) (21) Function f (t) —3.4t at t A/4 and f(t) —0.87t at t...
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· = < 01 (1 + -+ + + 2v)Z . (20) (21) Function f (t) —3.4t at t A/4 and f(t) —0.87t at t A/4. The vertex function (24) corresponds to the normalization (10): one magnon in the