Emptiness formation probability at finite temperature for the isotropic   Heisenberg chain
  We present an integral formula for a special correlation function of the isotropic spin-1/2 antiferromagnetic Heisenberg chain. The correlation function describes the probability for the occurrence of a string of consecutive up-spins as a function of temperature, magnetic field and length of the string. 
F. G\"ohmann, A. Kl\"umper, A. Seel