Correlation functions of the XXZ spin-1/2 chain: recent progress

J. M. Maillet Correlation functionsPhysical correlation functionsExample :〈ψ g |σ + 1 σ− m+1 |ψ g〉 ≡ 〈ψ g |E 121m∏j=2(E 11j+ E 22j) E21 m+1 |ψ g〉−→ sum of 2 m−1 elementary blocks: 〈ψ g |C( η 2 ) (A + D)m−1 ( η 2 ) B(η 2 )|ψ g〉Compact and symmetrized formula for the multiple action of A + D operators−→ Two point correlation functions :m−1〈σ α 1 σβ m+1 〉 = ∑n=0∮Cz∫ ∫d n+1 z d n λC λCµd 2 µ [f({λ, z})] m Γ αβn({λ, µ, z}) S h({λ, z})−→ Gives directly known free fermion results setting ∆ = 0−→ Asymptotics of two point functions for general ∆?– Typeset by FoilTEX – Florence 2003 9