58 research outputs found
The Green--Schwarz Superstring in Extended Configuration Space and Infinitely Reducible First Class Constraints Problem
The Green--Schwarz superstring action is modified to include some set of
additional (on-shell trivial) variables. A complete constraints system of the
theory turns out to be reducible both in the original and in additional
variable sectors. The initial first class constraints and second
class ones are shown to be unified with first and second class
constraints from the additional variables sector, resulting with
-covariant and linearly independent constraint sets. Residual
reducibility proves to fall on second class constraints only.Comment: 14 pages, LaTe
Comment about UV regularization of basic commutators in string theories
Recently proposed by Hwang, Marnelius and Saltsidis zeta regularization of
basic commutators in string theories is generalized to the string models with
non-trivial vacuums. It is shown that implementation of this regularization
implies the cancellation of dangerous terms in the commutators between Virasoro
generators, which break Jacobi identity.Comment: LaTeX, 9 pages, no figures, submitted to Physics Letters
Perturbative Computation of the Gluonic Effective Action via Polyaokov's World-Line Path Integral
The Polyakov world-line path integral describing the propagation of gluon
field quanta is constructed by employing the background gauge fixing method and
is subsequently applied to analytically compute the divergent terms of the one
(gluonic) loop effective action to fourth order in perturbation theory. The
merits of the proposed approach is that, to a given order, it reduces to
performing two integrations, one over a set of Grassmann and one over a set of
Feynman-type parameters through which one manages to accomodate all Feynman
diagrams entering the computation at once.Comment: 21 page
Particles with anomalous magnetic moment in external e.m. fields: the proper time formulation
In this paper we evaluate the expression for the Green function of a
pseudo-classical spinning particle interacting with constant electromagnetic
external fields by taking into account the anomalous magnetic and electric
moments of the particle. The spin degrees of freedom are described in terms of
Grassmann variables and the evolution operator is obtained through the
Fock-Schwinger proper time method.Comment: 10 page
Deformed Oscillator Algebras and Higher-Spin Gauge Interactions of Matter Fields in 2+1 Dimensions
We formulate a non-linear system of equations which describe higher-spin
gauge interactions of massive matter fields in 2+1 dimensional space-time and
explain some properties of the deformed oscillator algebra which underlies this
formulation. In particular we show that the parameter of mass of matter
fields is related to the deformation parameter in this algebra.Comment: LaTex, 12 pages, no figures; Invited talk at the International
Seminar Supersymmetry and Quantum Field Theory dedicated to the memory of
Dmitrij V. Volkov; Kharkov, January 1997; to appear in the proceeding
On the covariant quantization of tensionless bosonic strings in AdS spacetime
The covariant quantization of the tensionless free bosonic (open and closed)
strings in AdS spaces is obtained. This is done by representing the AdS space
as an hyperboloid in a flat auxiliary space and by studying the resulting
string constrained hamiltonian system in the tensionless limit. It turns out
that the constraint algebra simplifies in the tensionless case in such a way
that the closed BRST quantization can be formulated and the theory admits then
an explicit covariant quantization scheme. This holds for any value of the
dimension of the AdS space.Comment: 1+16 pages; v4 two clarifications adde
Conformal Higher Spin Symmetries of 4d Massless Supermultiplets and Invariant Equations in Generalized (Super)Space
Realization of the conformal higher spin symmetry on the 4d massless field
supermultiplets is given. The self-conjugated supermultiplets, including the
linearized SYM theory, are considered in some detail. Duality
between non-unitary field-theoretical representations and the unitary
doubleton--type representations of the 4d conformal algebra is
formulated in terms of a Bogolyubov transform. The set of 4d massless fields of
all spins is shown to form a representation of .
The obtained results are extended to the generalized superspace invariant
under supersymmetries. World line particle interpretation of the
free higher spin theories in the invariant (super)space is
given. Compatible with unitarity free equations of motion in the
invariant (super)space are formulated. A conjecture on the chain of
dualities in the higher spin
gauge theories is proposed.Comment: Latex, 63 pages; no figures.V2 Typos corrected, References updated.
V3.Typos correced, references and an explanation on the relationship with
previous work in section 4 are added. The version to appear in Phys.Rev.
String Theory, Unification and Quantum Gravity
An overview is given of the way in which the unification program of particle
physics has evolved into the proposal of superstring theory as a prime
candidate for unifying quantum gravity with the other forces and particles of
nature. A key concern with quantum gravity has been the problem of ultraviolet
divergences, which is naturally solved in string theory by replacing particles
with spatially extended states as the fundamental excitations. String theory
turns out, however, to contain many more extended-object states than just
strings. Combining all this into an integrated picture, called M-theory,
requires recognition of the r\^ole played by a web of nonperturbative duality
symmetries suggested by the nonlinear structures of the field-theoretic
supergravity limits of string theory.Comment: 29 pages, 13 figures, 3 tables; Lectures given at the 6th Aegean
Summer School "Quantum Gravity and Quantum Cosmology", Chora, Naxos Island,
Greece, 12-17 September 201
SU(2) Yang-Mills Theory with extended Supersymmetry in a Background Magnetic Field
The vacuum structure of N=2 (and N=4) SUSY Yang-Mills theory is analyzed in
detail by considering the effective potential for constant background scalar-
magnetic fields within different approximations. We compare the one-loop
approximation with- or without instanton improved effective coupling with the
one-loop result in the dual desription. For N=2 we find that non-perturbative
monopole degrees of freedom remove the non-trivial minima present in the
(improved) one-loop potential in the strong-coupling regime. The combination of
Yang-Mills and dual desription leads to a self-consistent effective potential
over the full range of background fields.Comment: 15 pages, Revtex, 3 figures, References added, section two shortened,
some minor remarks and corrections adde
D0 and D1 Brane With and Extended Symmetry
D0 brane (D-particle) and D1 brane actions possess first and second class
constraints that result in local symmetry. The symmetry of
the D-particle and the D1 brane is extended here into a larger symmetry
( and ) in a larger phase space by turning second class
constraints into first class. Different gauge fixings of these symmetries
result in different presentations of these systems while a "unitary" gauge
fixing of the new symmetry retrieves the original action with
symmetry. For D1 brane our extended phase space makes all
constraints into first class in the case of vanishing world sheet electric
field (namely string).Comment: A new section on D1 brane with extended kappa symmetry has been
added, references have been added. (18 pages, Latex file
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