Journal of Theoretical and Computational Studies
http://situs.jurnal.lipi.go.id/jtcs/
GAUGE INVARIANT FLUID LAGRANGIAN AND ITS APPLICATION TO COSMOLOGY
L.T. Handoko,A. Sulaiman and T.P. Djun
Group for Theoretical and Computational Physics, Research Center for Physics, Indonesian Institute of Sciences, Kompleks Puspiptek Serpong, Tangerang 15310, Indonesia P3 TISDA BPPT, BPPT Bld. II (19th floor), Jl. M.H. Thamrin 8, Jakarta 10340, Indonesia Department of Physics, Bandung Institute of Technology, Jl. Ganesha 10, Bandung 40132, Indonesia Department of Physics, University of Indonesia, Kampus UI Depok, Depok 16424, Indonesia
Abstract
A lagrangian for relativistic fluid systems with matters inside is developed using gauge principle. In the model, the gauge boson represents the fluid field in a form $A_mu equiv epsilon_mu , phi$, where $epsilon_mu$ contains the fluid kinematics and $phi$ is an auxiliary field representing the fluid distribution. This leads to a new relativistic equation of motion for fluid, but which further coincides to the classical Euler equation at nonrelativistic limit. The lagrangian is applied to model homogeneous universe as a bulk pure fluid system. Taking the simplest case of fluid with radial velocity and uniform distribution, the free energy density is calculated and its behaviour around Hubble distance is discussed.
