Dynamics of causal hydrodynamic fluctuations in an expanding system.

We develop a framework of causal hydrodynamic fluctuations in onedimensional expanding system performing linearisation of the hydrodynamic equations around the boost invariant solution. Through the description of spacetime 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. [ABSTRACT FROM AUTHOR]