High temperature expansion of emptiness formation probability for isotropic Heisenberg chain

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Recently, Göhmann, Klümper and Seel have derived novel integral formulas for the correlation functions of the spin-1/2 Heisenberg chain at finite temperature. We have found that the high temperature expansion (HTE) technique can be effectively applied to evaluate these integral formulas. Actually, as for the emptiness formation probability P(n) of the isotropic Heisenberg chain, we have found a general formula of the HTE for P(n) with arbitrary n ∈ Z≥ ₂ up to O((J/T)⁴). If we fix a magnetic field to a certain value, we can calculate the HTE to much higher order. For example, the order up to O((J/T)⁴²) has been achieved in the case of P(3) when h=0. We have compared these HTE results with the data by Quantum Monte Carlo simulations. They exhibit excellent agreements.