64 research outputs found
Tensionless String in the Notoph Background
We study the interaction between a tensionless (null) string and an
antisymmetric background field B_{ab} using a 2-component spinor formalism. A
geometric condition for the absence of such an interaction is formulated. We
show that only one gauge-invariant degree of freedom of the field B_{ab} does
not satisfy this condition. Identification of this degree of freedom with the
notoph field \phi of Ogievetskii-Polubarinov-Kalb-Ramond is suggested.
Application of a two-component spinor formalism allows us a reduction of the
complete system of non-linear partial differential equations and constraints
governing the interacting null string dynamics to a system of linear
differential equations for the basis spinors of the spin-frame. We find that
total effect of the interaction is contained in a single derivation coefficient
which is identified with the notoph field.Comment: 15 pages, no figures, RevTeX 3.
Computation of the minimum eigenvalue for a nonlinear Sturm-Liouville problem
© 2014, Pleiades Publishing, Ltd. A condition for the existence of a minimum eigenvalue corresponding to a positive eigenfunction of the nonlinear eigenvalue problem for an ordinary differential equation is determined. The problem is approximated by a mesh scheme of the finite element method. The convergence of approximate solutions to exact ones is studied. Theoretical results are illustrated by numerical experiments for a model problem
Massless Chiral Supermultiplets of Higher Spins and the -Twistor
Recently N. Berkovits, motivated by the supertwistor description of super Yang-Mills, considered the generalization of the -twistor construction to D=10 and applied it for a compact
covariant description of super Yang-Mills. This supports the
relevance of the -twistor as a supersymmetric twistor alternative to
the well-known supertwistor. The minimal breaking of superconformal symmetry is
an inherent property of the -twistor received from its fermionic
components, described by a Grassmannian vector instead of a Grassmannian scalar
in the supertwistor. The -twistor description of the
massless chiral supermultiplets with spins
is considered here. The description permits to restore the auxiliary fields
of the chiral supermultiplets absent in the supertwistor approach. The proposed
formalism is naturally generalized to and can be used for an
off-shell description of the corresponding super Yang-Mills theory.Comment: 15 page
Hydrodynamic type integrable equations on a segment and a half-line
The concept of integrable boundary conditions is applied to hydrodynamic type
systems. Examples of such boundary conditions for dispersionless Toda systems
are obtained. The close relation of integrable boundary conditions with
integrable reductions of multi-field systems is observed. The problem of
consistency of boundary conditions with the Hamiltonian formulation is
discussed. Examples of Hamiltonian integrable hydrodynamic type systems on a
segment and a semi-line are presented
Generalized action principle and extrinsic geometry for N=1 superparticle
It is proposed the generalized action functional for N=1 superparticle in
D=3,4,6 and 10 space-time dimensions. The superfield geometric approach
equations describing superparticle motion in terms of extrinsic geometry of the
worldline superspace are obtained on the base of the generalized action. The
off-shell superdiffeomorphism invariance (in the rheonomic sense) of the
superparticle generalized action is proved. It was demonstrated that the half
of the fermionic and one bosonic (super)fields disappear from the generalized
action in the analytical basis. Superparticle interaction with Abelian gauge
theory is considered in the framework of this formulation. The geometric
approach equations describing superparticle motion in Abelian background are
obtained.Comment: 31 pages. Late
Schild's Null Strings in Flat and Curved Backgrounds
Schild's null (tensionless) strings are discussed in certain flat and curved
backgrounds. We find closed, stationary, null strings as natural configurations
existing on the horizons of spacetimes which possess such null hypersurfaces.
Examples of these are obtained in Schwarzschild and Rindler spacetimes. A
dynamic null string is also identified in Rindler spacetime. Furthermore, a
general prescription (with explicit examples) is outlined by means of which
null string configurations can be obtained in a large class of cosmological
backgrounds.Comment: RevTex 3.0, 14 Pages, no figure
(Super)twistors and (super)strings
The Lagrangian formulation of the D=4 bosonic string and superstring in terms
of the (super)twistors is considered. The (super)twistor form of the equations
of motion is derived and the kappa-symmetry transformation for the
supertwistors is given. It is shown that the covariant kappa-symmetry gauge
fixation results in the action quadratic in the (super)twistor variables.Comment: LaTeX, 17 page
Null Strings in Schwarzschild Spacetime
The null string equations of motion and constraints in the Schwarzschild
spacetime are given. The solutions are those of the null geodesics of General
Relativity appended by a null string constraint in which the "constants of
motion" depend on the world-sheet spatial coordinate. Because of the extended
nature of a string, the physical interpretation of the solutions is completely
different from the point particle case. In particular, a null string is
generally not propagating in a plane through the origin, although each of its
individual points is. Some special solutions are obtained and their physical
interpretation is given. Especially, the solution for a null string with a
constant radial coordinate moving vertically from the south pole to the
north pole around the photon sphere, is presented. A general discussion of
classical null/tensile strings as compared to massless/massive particles is
given. For instance, tensile circular solutions with a constant radial
coordinate do not exist at all. The results are discussed in relation to
the previous literature on the subject.Comment: 16 pages, REVTEX, no figure
Simulation of the processes of plasma modification and vacuum metallization of polymer materials by the method of molecular dynamics
The article presents the results of the development of molecular dynamics models of modifications of polypropylene (PP) material in the plasma of a radio-frequency (RF) discharge and a copper coating deposit by magnetron sputtering on the surface of a polyethylene (PE) material. The model of the RF plasma modification process describes changes in the surface layers of the PP material upon interaction with low-energy plasma ions: the nature of the breaking of covalent bonds in macromolecules, the chemical composition of sputtered particles, and changes in the ordering of the supramolecular structure. The model of the vacuum metallization process describes the processes of the introduction of metal atoms into the polymer structure, the change in the conformation of macromolecules, the formation of macroradicals with uncompensated chemical bonds, and the formation of an interfacial layer between the polymer and the metal coating
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