A recent study has elucidated the exact relationship between the Eckart and Landau-Lifshitz frames, two key formalisms in relativistic dissipative hydrodynamics. Researchers have shown that the choice of hydrodynamic frame directly influences the numerical values of transport coefficients, such as thermal conductivity. This work is fundamental for the consistent interpretation of data obtained from heavy-ion collision experiments, lattice quantum chromodynamics (lattice QCD) calculations, and kinetic theories.

The study reveals that the Landau-Lifshitz thermal conductivity is suppressed relative to the Eckart conductivity, a difference that increases with rising temperature and baryonic chemical potential. To reach this conclusion, a baryon-rich relativistic fluid described by a Boltzmann nucleon gas equation of state was used. Despite these differences in transport coefficients, a linearized analysis of sound propagation confirmed that the sound attenuation coefficient remains identical in both frames, underscoring the invariance of physical observables.

These findings suggest that the frame dependence of transport coefficients reflects only the different ways dissipative effects are decomposed into heat flows and diffusion currents, while the underlying transport physics remains unchanged. The research emphasizes the necessity of specifying the hydrodynamic frame used when comparing transport coefficients across different theoretical and experimental contexts, which will enable a more precise and unified understanding of relativistic fluid dynamics.