Dynamics of causal hydrodynamic fluctuations in an expanding system

We develop a framework of causal hydrodynamic fluctuations in one-dimensional expanding system performing linearisation of the hydrodynamic equations around the boost invariant solution. Through the description of space-time evolution of thermodynamic variables and flow velocity, we find a novel phenomenon that the structure of thermodynamic variables is almost frozen. We also show that two-particle correlation functions of final hadrons after freezeout are closely related with the mass of hadrons and properties of the medium such as viscosity, relaxation time and equation of state.