Due to recent experimental achievements with trapped ultracold atoms, the properties of the 1D non-relativistic Bose gas are of great interest. In many experimental setups the behaviour of the particles is very well described by the Lieb-Liniger model which in many aspects can be regarded as a theoretical benchmark in the research of integrable models. In spite of its integrability, calculating correlation functions in the model is notoriously difficult. In the talk I will propose a novel approach to compute expectation values and other physical quantities in the Lieb-Liniger model. The method is based on the fact that in the repulsive case the S-matrix, the Lagrangian and the operators can be obtained from a certain non-relativistic limit of the sinh-Gordon model. This observation allows us to compute expectation values both at zero and finite temperature. Among other results, I present the computation of the three-body correlation function at finite temperature, which is closely related to the recombination rate of the gas.
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