Symmetry (physics)

About: Symmetry (physics) is a research topic. Over the lifetime, 26435 publications have been published within this topic receiving 500189 citations. The topic is also known as: symmetry (physics) & physical symmetry.

Nonlinear causality of general first-order relativistic viscous hydrodynamics

Abstract: Effective theory arguments are used to derive the most general energy-momentum tensor of a relativistic viscous fluid with an arbitrary equation of state (in the absence of other conserved currents) that is first-order in the derivatives of the energy density and flow velocity and does not include extended variables such as in Mueller-Israel-Stewart-like theories. This energy-momentum tensor leads to a causal theory, provided one abandons the usual conventions for the out-of-equilibrium hydrodynamic variables put forward by Landau-Lifshitz and Eckart. In particular, causality requires nonzero out-of-equilibrium energy density corrections and heat flow. Conditions are found to ensure linear stability around equilibrium in flat space-time. We also prove local existence and uniqueness of solutions to the equations of motion. Our causality, existence, and uniqueness results hold in the full nonlinear regime, without symmetry assumptions, in four space-time dimensions, with or without coupling to Einstein’s equations, and are mathematically rigorously established. Furthermore, a kinetic theory realization of this energy-momentum tensor is also provided

Asymmetric nuclear matter based on chiral two- and three-nucleon interactions

Abstract: We calculate the properties of isospin-asymmetric nuclear matter based on chiral nucleon-nucleon (NN) and three-nucleon (3N) interactions. To this end, we develop an improved normal-ordering framework that allows us to include general 3N interactions starting from a plane-wave partial-wave-decomposed form. We present results for the energy per particle for general isospin asymmetries based on a set of different Hamiltonians, study their saturation properties, the incompressibility, symmetry energy, and also provide an analytic parametrization for the energy per particle as a function of density and isospin asymmetry.

New class of effective field theories from embedded branes.

Abstract: We present a new general class of four-dimensional effective field theories with interesting global symmetry groups These theories arise from purely gravitational actions for ($3+1$)-dimensional branes embedded in higher dimensional spaces with induced gravity terms The simplest example is the well known Galileon theory, with its associated Galilean symmetry, arising as the limit of a DGP brane world However, we demonstrate that this is a special case of a much wider range of theories, with varying structures, but with the same attractive features such as second order equations In some circumstances, these new effective field theories allow potentials for the scalar fields on curved space, with small masses protected by nonlinear symmetries Such models may prove relevant to the cosmology of both the early and late universe

Symmetry-breaking bifurcations in resonant surface waves

Abstract: Surface waves in a nearly square container subjected to vertical oscillations are studied. The theoretical results are based on the analysis of a derived set of normal form equations, which represent perturbations of systems with 1:1 internal resonance and with D4 symmetry. Bifurcation analysis of these equations shows that the system is capable of periodic and quasi-periodic standing as well as travelling waves. The analysis also identifies parameter values at which chaotic behaviour is to be expected. The theoretical results are verified with the aid of some experiments.

Symmetry energy at subnuclear densities and nuclei in neutron star crusts

Abstract: Department of Materials Science, Kochi University, Akebono-cho, Kochi 780-8520, Japan(Dated: February 9, 2008)We examine how the properties of inhomogeneous nuclear matter at subnuclear densities dependon the density dependence of the symmetry energy. Using a macroscopic nuclear model we calculatethe size and shape of nuclei in neutron star matter at zero temperature in a way dependent onthe density dependence of the symmetry energy. We find that for smaller symmetry energy atsubnuclear densities, corresponding to larger density symmetry coefficient L, the charge number ofnuclei is smaller, and the critical density at which matter with nuclei or bubbles becomes uniform islower. The decrease in the charge number is associated with the dependence of the surface tensionon the nuclear density and the density of a sea of neutrons, while the decrease in the critical densitycan be generally understood in terms of proton clustering instability in uniform matter.