Bosonic symmetries of the Dirac equation

We have found on the basis of the symmetry analysis of the standard Dirac equation with nonzero mass the new physically meaningful features of this equation. The new bosonic symmetries of the Dirac equation in both the Foldy-Wouthuysen and the Pauli-Dirac representations are found, among which (together with the 32-dimensional pure matrix algebra of invariance) the new spin s=(1,0) multiplet Poincaré symmetry is proved. In order to carry out the corresponding proofs a 64-dimensional extended real Clifford-Dirac algebra is put into consideration.     

Yangian symmetries and integrability of the Dirac equation with spin symmetry

We show that a Yangian symmetry, namely, Y(su(2))$Y\left(su\left(2\right)\right)$, exists in the Dirac equation with spin symmetry when the potential term takes a Coulomb form. We construct the generators of Y(su(2))$Y\left(su\left(2\right)\right)$ explicitly and get the energy spectrum of this model from the representation theory for Y(su(2))$Y\left(su\left(2\right)\right)$. We also show that this model is integrable, from RTT relations.     

The nonlinear Dirac equation in Bose-Einstein condensates: Foundation and symmetries

We show that Bose-Einstein condensates in a honeycomb optical lattice can be described by a nonlinear Dirac equation in the long wavelength, mean field limit. Unlike nonlinear Dirac equations posited by particle theorists, which are designed to preserve the principle of relativity, i.e., Poincaré covariance, the nonlinear Dirac equation for Bose-Einstein condensates breaks this symmetry. We present a rigorous derivation of the nonlinear Dirac equation from first principles. We provide a thorough discussion of all symmetries broken and maintained.     

Approximate eigensolutions of Dirac equation for the superposition Hellmann potential under spin and pseudospin symmetries

The Hellmann potential is simply a superposition of an attractive Coulomb potential ?a/r plus a Yukawa potential be^{?δ r} /r. The generalized parametric Nikiforov–Uvarov (NU) method is used to examine the approximate analytical energy eigenvalues and two-component wave function of the Dirac equation with the Hellmann potential for arbitrary spin-orbit quantum number κ in the presence of exact spin and pseudospin (p-spin) symmetries. As a particular case, we obtain the energy eigenvalues of the pure Coulomb potential in the non-relativistic limit.     

On the algebra of symmetries of Laplace and Dirac operators

We consider a generalization of the classical Laplace operator, which includes the Laplace–Dunkl operator defined in terms of the differential-difference operators associated with finite reflection groups called Dunkl operators. For this Laplace-like operator, we determine a set of symmetries commuting with it, in the form of generalized angular momentum operators, and we present the algebraic relations for the symmetry algebra. In this context, the generalized Dirac operator is then defined as a square root of our Laplace-like operator. We explicitly determine a family of graded operators which commute or anticommute with our Dirac-like operator depending on their degree. The algebra generated by these symmetry operators is shown to be a generalization of the standard angular momentum algebra and the recently defined higher-rank Bannai–Ito algebra.     

On the Dirac equation

A connection is established between solutions of the Dirac equation (for an electron in a constant magnetic field) and those of the wave equation for a particle with zero mass.Translated from Izvestiya VUZ. Fizika, No. 12, pp. 96–100, December, 1973.     

Dirac equation and the Ivanenko-Landau-Kähler equation

We consider spinor theory within the framework of an inhomogeneous differential forms formalism. We also consider the possibility of describing fermions with the Ivanenko-Landau-Kähler equation. The relations between these two equations are studied.     

Dynamical symmetries of the Geodesic equation

A class of dynamical symmetries for the Euler-Lagrange equations corresponding to the LagrangianL=(1/2)g _ab q ^a q ^b is determined. The members of the class are closely related to tensor fields defined on the configuration space. First integrals generated by the dynamical symmetries through deformation of a given first integral are then examined. Noether-type conserved quantities whose expression depends only on the dynamical symmetry are also explicitly exhibited. Applications to general relativity are also pointed out in the course of the discussion.     

Geometrical symmetries of the Universal equation

Abstract

It is shown that the group of geometrical symmetries of the Universal equation of D-dimensional space coincides with SL(D + 1, R).     

Generalization of the Williams--Landel--Ferry equation

Based on the model of Gibbs-Di Marzio we write the logarithmic shift factor without explicit knowledge of the form for the entropy, an expression which enables us to write a generalization of the Williams--Landel--Ferry equation. Comparison with the empirical relation of Williams--Landel--Ferry and use of the fact that the model exhibits the existence of a isoentropic temperature T₀ for which the configurational entropy of the system vanishes, leads to a value of the isoentropic temperature for which the configurational entropy of the system vanishes. The form for the specific heat proposed by Dowell and Di Marzio based on the lattice model of Gibbs-Di Marzio for the glass transition of polymeric substances, has been used by García-Colín et al. to find the molar configurational entropy (MCE) of glass. Knowledge of the form of the MCE, allows us to find an expression for the critical configurational entropy (S^*_c) and a form for the potential energy hindering the cooperative rearrangement per monomer segment (Δμ).     

Superspace formulation of the dynamical symmetries of the Dirac magnetic monopole

The superspace formulation for the dynamical supersymmetry of the Pauli system in the presence of a Dirac magnetic monopole is presented. It is used to prove that Osp(1, 1) is the largest dynamical invariance group of this system. The action of finite transformations on the parameters of superspace and on the supervariables is given.     

Tensorial representation of the Dirac equation

We discuss tensor representations of the Dirac equation using a geometric approach. We find that the mass zero Dirac equations can be represented by Maxwell equations having a source which obeys the empty space wave equation. We also obtain a relation for the source in terms ofE andH. In the case of mass not equal to zero a difficulty is encountered in removing the constant spinors¯ _Aand¯ _A.We find that the arbitrary constant spinors can be eliminated in a spinor theory based on the Klein-Gordon equation.     

Linear and nonlinear Dirac equation

Using the usual matrix representation of Clifford algebra of spacetime, quantities independent of the choice of a representation in the Dirac theory are examined, relativistic invariance of the theory is discussed, and a nonlinear equation is proposed. The equation presents no negative energy waves and gives the same results as the linear theory for hydrogen atom.     

Algebraic properties of the Dirac equation

The first-order symmetry operators of the Dirac equation are classified according to their tensor properties under transformations of the homogeneous Lorentz group; a minimal system of generators for the ring of symmetry operators of the free Dirac equation is obtained, and the physical meaning of the spin operators is considered; fields are found which admit symmetry operators of first order.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 84–89, February, 1972.The author is grateful to V. N. Shapovalov for discussions and valuable suggestions.     

Fluid-dynamical representations of the Dirac equation

A relative kinetic mass operator is defined bym =c ⁻²·(E −eΦ), and it is shown that bt using it in a symmetric form one can correlate the (charge) velocity operatorα in the Dirac theory exactly with the general quantum mechanical momentum —ih∇. Then the net force, defined as the rate of change of the relative momentum with time, is exactly equal to the Lorentz force. The contribution due to the time variation of mass equals the negative of space variation of the scalar potential, the Newtonian force, whereas the time variation of the charge current absorbs the entire vector potential dependence. The analogous Euler equations can be written either in terms of the charge current or in terms of the mass current. For a many particle system one needs the usual net single particle parameters and the consideration of both the direct and exchange contributions of the two particle interaction. These Euler equations yield two different conditions of the stationary state. It is shown that the charge-current condition is necessary but not sufficient, whereas the mass-current condition retains the appropriate scalar potential dependence. These two conditions are compared for the spherically symmetric case. The charge density, charge current and relative mass current are tabulated for atomic spinors. Differences between the quantum and classical forces for the H ₂ ⁺ molecular ion exhibit the inadequacy of ordinary atomic spinor basis in forming molecular spinors.     

On a Lorentz Non-Invariant Generalization of the Dirac Equation

A generalized Dirac equation is presented as a model theory of disturbed Lorentz invariance. The physical properties of this model and experimental consequences are discussed. A program is described how such Lorentz noninvariant equations may be produced by cosmological induction of local causal structure.     

Generalized and potential symmetries of the Rudenko-Robsman equation

The paper presents a concrete study of the existence of generalized and potential symmetries for the 1+1 dimensional version of the Rudenko-Robsman equation, an interesting fourth-order partial differential equation that describes the evolution of nonlinear waves in a dispersive medium. As the main results, the existence of a two-parameter algebra of generalized symmetries and of an infinite-dimensional algebra when potential symmetries are taken into account is proven.