Time dependent correlation functions in the Heisenberg XX0 chain in the external transverse magnetic field are calculated. For a finite chain normalized mean values of local spin products are represented as determinants of NxN matrices, N being the number of quasiparticles in the corresponding eigenstate of the Hamiltonian. In the thermodynamical limit (infinitely long chain), correlation functions are expressed in terms of Fredholm determinants of linear integral operators. (author) 24 refs.
Colomo, F;  Izergin, A G;  Korepin, V E;  Tognetti, V 
- Istituto Nazionale di Fisica Nucleare, Florence (Italy)
- Istituto Nazionale di Fisica Nucleare, Pisa (Italy)
- State Univ. of New York, Stony Brook, NY (United States). Inst. for Theoretical Physics
- Firenze Univ. (Italy). Dipt. di Fisica