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.

Holography and off-center collisions of localized shock waves

Abstract: Using numerical holography, we study the collision, at non-zero impact parameter, of bounded, localized distributions of energy density chosen to mimic relativistic heavy ion collisions, in strongly coupled $$ \mathcal{N}=4 $$ supersymmetric Yang-Mills theory. Both longitudinal and transverse dynamics in the dual field theory are properly described. Using the gravitational description, we solve 5D Einstein equations with no dimensionality reducing symmetry restrictions to find the asymptotically anti-de Sitter spacetime geometry. Implications of our results on the understanding of early stages of heavy ion collisions, including the development of transverse radial flow, are discussed.

Symmetry and stability in Taylor Couette flow

Abstract: We study the flow of a fluid between concentric rotating cylinders (the Taylor problem) by exploiting the symmetries of the system. The Navier–Stokes equations, linearized about Couette flow, possess two zero and four purely imaginary eigenvalues at a suitable value of the speed of rotation of the outer cylinder. There is thus a reduced bifurcation equation on a six-dimensional space which can be shown to commute with an action of the symmetry group $O(2) \times SO(2)$. We use the group structure to analyze this bifurcation equation in the simplest (nondegenerate) case and to compute the stabilities of solutions. In particular, when the outer cylinder is counterrotated we can obtain transitions which seem to agree with recent experiments of Andereck, Liu, and Swinney [1984]. It is also possible to obtain the “main sequence” in this model. This sequence is normally observed in experiments when the outer cylinder is held fixed.

Yukawa textures with an anomalous horizontal abelian symmetry

Abstract: The observed hierarchy of quark and lepton masses and mixings may be obtained by adding an abelian family symmetry to the Minimal Supersymmetric Model and coupling quarks and leptons to an electroweak singlet scalar field. In a large class of such models, this symmetry suffers from anomalies which must be compensated by the Green-Schwarz mechanism; this in turn fixes the electroweak mixing angle to be $\sin^2 \theta_W = 3/8$ at the string scale, without any assumed GUT structure. The analysis is extended to two distinct generalisations of the Standard Model: neutrino masses and mixings and R-parity violating interactions.

Stability of the higher-bound states in a saturable self-focusing medium

Abstract: We present an investigation of the stability of the cylindrically symmetric higher-bound states that can be formed in a self-focusing medium with saturation. The higher-bound states are found to display transverse instabilities that break the azimuthal symmetry of the system. An approximate analytic theory is presented that correctly describes the qualitative variations of the numerically calculated instability growth rates.

Generalized global symmetries in states with dynamical defects: The case of the transverse sound in field theory and holography

Abstract: In this work, we show how states with conserved numbers of dynamical defects (strings, domain walls, etc.) can be understood as possessing generalized global symmetries even when the microscopic origins of these symmetries are unknown. Using this philosophy, we build an effective theory of a $2+1$-dimensional fluid state with two perpendicular sets of immersed elastic line defects. When the number of defects is independently conserved in each set, then the state possesses two one-form symmetries. Normally, such viscoelastic states are described as fluids coupled to Goldstone bosons associated with spontaneous breaking of translational symmetry caused by the underlying microscopic structure---the principle feature of which is a transverse sound mode. At the linear, nondissipative level, we verify that our theory, based entirely on symmetry principles, is equivalent to a viscoelastic theory. We then build a simple holographic dual of such a state containing dynamical gravity and two two-form gauge fields, and use it to study its hydrodynamic and higher-energy spectral properties characterized by nonhydrodynamic, gapped modes. Based on the holographic analysis of transverse two-point functions, we study consistency between low-energy predictions of the bulk theory and the effective boundary theory. Various new features of the holographic dictionary are explained in theories with higher-form symmetries, such as the mixed-boundary-condition modification of the quasinormal mode prescription that depends on the running coupling of the boundary double-trace deformations. Furthermore, we examine details of low- and high-energy parts of the spectrum that depend on temperature, line defect densities and the renormalization group scale.