Noncommutative Dirac-Born-Infeld Action for D-brane

We derive the noncommutative Dirac-Born-Infeld action for the $D$-brane, which governs dynamics of $D$-brane with a NS-NS $B$-field in the low energy regime. Depending on some details of the path integral prescriptions, both ordinary Dirac-Born-Infeld action and noncommutative one can be obtained by evaluating the same Polyakov string path integral for the open string ending on the $D$-brane. Thus, it establishes the equivalence of the noncommutative Dirac-Born-Infeld action and the ordinary one.Comment: 13 Pages, RevTex, added reference

Higher spins dynamics in the closed string theory

The general $\sigma$-model-type string action including both massless and massive higher spins background fields is suggested. Field equations for background fields are followed from the requirement of quantum Weyl invariance. It is shown that renormalization of the theory can be produced level by level. The detailed consideration of background fields structure and corresponding fields equations is given for the first massive level of the closed bosonic string.Comment: 11 pages, report TSU/QFTD-36/9

One-loop counterterms for the dimensional regularization of arbitrary Lagrangians

We present master formulas for the divergent part of the one-loop effective action for an arbitrary (both minimal and nonminimal) operators of any order in the 4-dimensional curved space. They can be considered as computer algorithms, because the one-loop calculations are then reduced to the simplest algebraic operations. Some test applications are considered by REDUCE analytical calculation system.Comment: 39 pages, Latex, 3 PS figures, replaced with published versio

Generalized canonical quantization of bosonic string model in massive background fields

A method of constructing a canonical gauge invariant quantum formulation for a non-gauge classical theory depending on a set of parameters is advanced and then applied to the theory of closed bosonic string interacting with massive background fields. It is shown that within the proposed formulation the correct linear equations of motion for background fields arise.Comment: 4 pages, LaTeX, talk given by I.L. Buchbinder at the Second Conference on Constrained Dynamics and Quantum Gravity, S. Margherita Ligure, September 17-21 199

New Vector Field and BRST Charges in 2-form Einstein Gravity

A new vector field is introduced into 2-form Einstein gravity in four dimensions to restore a large symmetry of its topological version. Two different expressions for the BRST charge are given in the system: one of them associated with a set of irreducible symmetries and the other with a set of on-shell reducible symmetries.Comment: 9 pages, phyzzx, TIT/HEP-206/COSMO-2

Minimal conductivity in bilayer graphene

Using the Landauer formula approach, it is proven that minimal conductivity of order of $e^{2}/h$ found experimentally in bilayer graphene is its intrinsic property. For the case of ideal crystals, the conductivity turns our to be equal to $e^{2}/2h$ per valley per spin. A zero-temperature shot noise in bilayer graphene is considered and the Fano factor is calculated. Its value $1-2/\pi$ is close to the value 1/3 found earlier for the single-layer graphene.Comment: 3 pages, 1 figur

The One Loop Effective Action of QED for a General Class of Electric Fields

We compute the effective action of QED at one loop order for an electric field which points in the $\hat{z}$ direction and depends arbitrarily upon the light cone time coordinate, $x^+ = (x^0 + x^3)/\sqrt{2}$. This calculation generalizes Schwinger's formula for the vacuum persistence probability in the presence of a constant electric field.Comment: 9 pages, LaTeX 2 epsilo

Massive fields dynamics in open bosonic string theory

We consider the theory of open bosonic string in massive background fields. The general structure of renormalization is investigated. A general covariant action for a string in background fields of the first massive level is suggested and its symmetries are described. Equations of motion for the background fields are obtained by demanding that the renormalized operator of the energy-momentum tensor trace vanishes.Comment: 13 page

Path Integrals, BRST Identities and Regularization Schemes in Nonstandard Gauges

The path integral of a gauge theory is studied in Coulomb-like gauges. The Christ-Lee terms of operator ordering are reproduced {\it{within}} the path integration framework. In the presence of fermions, a new operator term, in addition to that of Christ-Lee, is discovered. Such kind of terms is found to be instrumental in restoring the invariance of the effective Lagrangian under a field dependent gauge transformation, which underlies the BRST symmetry. A unitary regularization scheme which maintains manifest BRST symmetry and is free from energy divergences is proposed for a nonabelian gauge field.Comment: 40 pages and 2 figure