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.

Determining horizontal symmetry from neutrino mixing.

Abstract: We argue that the best way to determine horizontal symmetry is from neutrino mixing and proceed to show that the only finite group capable of yielding the tribimaximal mixing for all Yukawa couplings is S{sub 4}, or any group containing it. The method used is largely group theoretical, but it can be implemented by dynamical schemes in which the Higgs expectation values introduced to break S{sub 4} spontaneously are uniquely determined up to an unknown scale for each.

Spin symmetry in the antinucleon spectrum.

Abstract: We discuss spin and pseudospin symmetry in the spectrum of single nucleons and single antinucleons in a nucleus. As an example we use relativistic mean field theory to investigate single antinucleon spectra. We find a very well developed spin symmetry in single antineutron and single antiproton spectra. The dominant components of the wave functions of the spin doublet are almost identical. This spin symmetry in antiparticle spectra and the pseudospin symmetry in particle spectra have the same origin. However, it turns out that the spin symmetry in antinucleon spectra is much better developed than the pseudospin symmetry in normal nuclear single particle spectra.

On a long-standing conjecture of E. De Giorgi: symmetry in 3D for general nonlinearities and a local minimality property

Abstract: This paper studies a conjecture made by De Giorgi in 1978 concerning the one-dimensional character (or symmetry) of bounded, monotone in one direction, solutions of semilinear elliptic equations Δu=F′(u) in all of R n . We extend to all nonlinearities F∈C 2 the symmetry result in dimension n=3 previously established by the second and third authors for a class of nonlinearities F which included the model case F′(u)=u 3−u. The extension of the present paper is based on new energy estimates which follow from a local minimality property of u. In addition, we prove a symmetry result for semilinear equations in the halfspace R + 4. Finally, we establish that an asymptotic version of the conjecture of De Giorgi is true when n≤8, namely that the level sets of u are flat at infinity.

The effects of phase matching method and of uniaxial crystal symmetry on the polar distribution of second-order non-linear optical polarization

Abstract: The index matching technique of Giordmaine and Maker has been extended to include the more general three-wave interaction. Two fundamentally different experimental arrangements may be considered; one has the two low frequency waves in parallel polarizations and the other has these waves in orthogonal polarizations. The equations relating the phase matching angle in uniaxial crystals to the crystal birefringence, dispersion, and the frequencies of the three waves are given. These equations allow a cone of phase matched directions to be generated about the crystal optic axis. The effect of the symmetry properties of the second-order polarizability tensor on the strength of the phase matched output signal at particular azimuthal angles is discussed for all non-centro-symmetrical uniaxial crystal classes. The particular form of the second-order polarizability tensor for each of the uniaxial crystals is tabulated assuming that Kleinman's symmetry conjecture is valid.