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B. Geyer

Publications and source records attributed to B. Geyer.

At least 55 records · Page 3Linked to original sources
arXiv2003

Higher dimensional analogue of the Blau-Thompson model and N_T=8, D=2 Hodge-type cohomological gauge theories

The higher dimensional analogue of the Blau-Thompson model in D=5 is constructed by a N_T=1 topological twist of N=2, D=5 super Yang-Mills theory. Its dimenional reduction to D=4 and D=3 gives rise to the B-model and N_T=4 equivariant extension of the Blau-Thompson model, respectively. A further dimensional reduction to D=2 provides another example of a N_T=8 Hodge-type cohomological theory with global symmetry group SU(2) \otimes \bar SU(2). Moreover, it is shown that this theory possesses actually a larger global symmetry group SU(4) and and that it agrees with the N_T=8 topological twisting of N+16, D=2 super Yang-Mills theory.

hep-th↗
arXiv2003

Perturbation approach to the Casimir force between two bodies made of different real metals

The Casimir force acting between two test bodies made of different metals is considered. The finiteness of the conductivity of the metals is taken into account perturbatively up to the fourth order of the relative penetration depths of electromagnetic zero-point oscillations into the metals. The influence of nonzero temperature is computed explicitly for separate orders of perturbation and found to be important in the zeroth and first orders only. The configurations of two parallel plates and a sphere (spherical lens) above a plate are considered made of $Au$ and $Cr$. The obtained results can be used to take into account also the surface roughness. Thus, the total amount of the Casimir force between different metals with all correction factors is determined. This may be useful in various applications.

quant-ph↗
arXiv2003

On Problems of the Lagrangian Quantization of W3-gravity

We consider the two-dimensional model of W3-gravity within Lagrangian quantization methods for general gauge theories. We use the Batalin-Vilkovisky formalism to study the arbitrariness in the realization of the gauge algebra. We obtain a one-parametric non-analytic extension of the gauge algebra, and a corresponding solution of the classical master equation, related via an anticanonical transformation to a solution corresponding to an analytic realization. We investigate the possibility of closed solutions of the classical master equation in the Sp(2)-covariant formalism and show that such solutions do not exist in the approximation up to the third order in ghost and auxiliary fields.

hep-th↗
arXiv2002

Canonical form of Euler-Lagrange equations and gauge symmetries

The structure of the Euler-Lagrange equations for a general Lagrangian theory is studied. For these equations we present a reduction procedure to the so-called canonical form. In the canonical form the equations are solved with respect to highest-order derivatives of nongauge coordinates, whereas gauge coordinates and their derivatives enter in the right hand sides of the equations as arbitrary functions of time. The reduction procedure reveals constraints in the Lagrangian formulation of singular systems and, in that respect, is similar to the Dirac procedure in the Hamiltonian formulation. Moreover, the reduction procedure allows one to reveal the gauge identities between the Euler-Lagrange equations. Thus, a constructive way of finding all the gauge generators within the Lagrangian formulation is presented. At the same time, it is proven that for local theories all the gauge generators are local in time operators.

hep-th↗
arXiv2002

Extended BRST quantization in general coordinates

We propose an extended BRST invariant Lagrangian quantization scheme of general gauge theories based on explicit realization of "modified triplectic algebra" in general coordinates. All the known Lagrangian quantization schemes based on the extended BRST symmetry are obtained by specifying the (free) parameters of that method.

hep-th↗
arXiv2002

Topological gauge theories with antisymmetric tensor matter fields

A new type of topological matter interactions involving second-rank antisymmetric tensor matter fields with an underlying $N_T \geq 1$ topological supersymmetry are proposed. The construction of the 4-dimensional, $N_T = 1$ Donaldson-Witten theory, the $N_T = 1$ super-BF model and the $N_T = 2$ topological B-model with tensor matter are explicitly worked out.

hep-th↗
arXiv2001

Casimir force under the influence of real conditions

The Casimir force is calculated analytically for configurations of two parallel plates and a spherical lens (sphere) above a plate with account of nonzero temperature, finite conductivity of the boundary metal and surface roughness. The permittivity of the metal is described by the plasma model. It is proved that in case of the plasma model the scattering formalism of quantum field theory in Matsubara formulation underlying Lifshitz formula is well defined and no modifications are needed concerning the zero-frequency contribution. The temperature correction to the Casimir force is found completely with respect to temperature and perturbatively (up to the second order in the relative penetration depth of electromagnetic zero-point oscillations into the metal) with respect to finite conductivity. The asymptotics of low and high temperatures are presented and contributions of longitudinal and perpendicular modes are determined separately. Serving as an example, aluminium test bodies are considered showing good agreement between the obtained analytical results and previously performed numerical computations. The roughness correction is formally included and formulas are given permitting to calculate the Casimir force under the influence of all relevant factors.

quant-ph↗
arXiv2001

Twisted N=8, D=2 super Yang-Mills theory as example of a Hodge-type cohomological theory

It is shown that the dimensional reduction of the N_T=2, D=3 Blau-Thompson model to D=2, i.e., the novel topological twist of N=8, D=2 super Yang-Mills theory, provides an example of a Hodge-type cohomological theory. In that theory the generators of the topological shift, co-shift and gauge symmetry, together with a discrete duality operation, are completely analogous to the de Rham cohomology operators and the Hodge *-operation.

hep-th↗
arXiv2000

Inflationary Brans-Dicke Quantum Universe II: Particular evolutions and stability analysis

We made an analysis of the equations of motion which are obtained from the one - loop effective action for Brans-Dicke gravity with N dilaton - coupled massless fermions in a time-dependent conformally flat background. Various particular solutions, including the well-known stationary one, of the corresponding set of first-order differential equations are given. Some of these solutions describe an expanding time-dependent Universe with increasing, constant or also decreasing dilaton. This is illustrated by a numerical analysis. For the nonstationary solutions a stability analysis is given.

hep-ph↗
arXiv2000

Casimir force at both non-zero temperature and finite conductivity

We find the joint effect of non-zero temperature and finite conductivity onto the Casimir force between real metals. Configurations of two parallel plates and a sphere (lens) above a plate are considered. Perturbation theory in two parameters (the relative temperature and the relative penetration depth of zero point oscillations into the metal) is developed. Perturbative results are compared with computations. Recent evidence concerning possible existence of large temperature corrections at small separations between the real metals is not supported.

quant-ph↗
arXiv2000

New constraints for non-Newtonian gravity in nanometer range from the improved precision measurement of the Casimir force

We obtain constraints on non-Newtonian gravity following from the improved precision measurement of the Casimir force by means of atomic force microscope. The hypothetical force is calculated in experimental configuration (a sphere above a disk both covered by two metallic layers). The strengthenings of constraints up to 4 times comparing the previous experiment and up to 560 times comparing the Casimir force measurements between dielectrics are obtained in the interaction range 5.9 nm$\leqλ\leq 115 $nm. Recent speculations about the presence of some unexplained attractive force in the considered experiment are shown to be unjustified.

hep-ph↗
arXiv1999

Covariant Quantization with Extended BRST Symmetry

A short rewiev of covariant quantization methods based on BRST-antiBRST symmetry is given. In particular problems of correct definition of Sp(2) symmetric quantization scheme known as triplectic quantization are considered.

hep-th↗
arXiv1999

The Virtual Compton Amplitude in the Generalized Bjorken Region: Twist--2 Contributions

A systematic derivation is presented of the twist-2 anomalous dimensions of the general quark and gluon light-ray operators in the generalized Bjorken region in leading order both for unpolarized and polarized scattering. Various representations of the anomalous dimensions are derived both in the non-local and the local light cone expansion and their properties are discussed in detail. Evolution equations for these operators are derived using different representations. General two- and single-variable evolution equations are presented for the expectation values of these operators for non-forward scattering. The Compton amplitude is calculated in terms of these distribution amplitudes. In the limit of forward scattering a new derivation of the integral relations between the twist-2 contributions to the structure functions is given. Special limiting cases which are derived from the general relations are discussed, as the forward case, near-forward scattering, and vacuum-meson transition. Solutions of the two-variable evolution equations for non-forward scattering are presented.

hep-ph↗
arXiv1999

Osp(1,2)-covariant Lagrangian quantization of reducible massive gauge theories

The osp(1,2)-covariant Lagrangian quantization of irreducible gauge theories [hep-th/9712204] is generalized to L-stage reducible theories. The dependence of the generating functional of Green's functions on the choice of gauge in the massive case is dicussed and Ward identities related to osp(1,2) symmetry are given. Massive first stage theories with closed gauge algebra are studied in detail. The generalization of the Chapline-Manton model and topological Yang-Mills theory to the case of massive fields is consedered as examples.

hep-th↗
arXiv1999

Decomposition of nonlocal light-cone operators into harmonic operators of definite twist

Bilocal light-ray operators which are Lorentz scalars, vectors or antisymmetric tensors, and which appear in various hard scattering QCD processes, are decomposed into operators of definite twist. These operators are harmonic tensor functions and their Taylor expansion consists of (traceless) local light-cone operators with span irreducible representations of the Lorentz group with definite spin j and common geometric twist (= dimension - spin). Some applications concerning the nonforward matrix elements of these operators and the generalization fo conformal light-cone operators of definite twist is considered. The group theoretical background of the method has been made clear.

hep-th↗