697 research outputs found
Nonperturbative solution of the Nonconfining Schwinger Model with a generalized regularization
Nonconfining Schwinger Model [AR] is studied with a one parameter class of
kinetic energy like regularization. It may be thought of as a generalization
over the regularization considered in [AR]. Phasespace structure has been
determined in this new situation. The mass of the gauge boson acquires a
generalized expression with the bare coupling constant and the parameters
involved in the regularization. Deconfinement scenario has become transparent
at the quark-antiquark potential level.Comment: 13 pages latex fil
The coupling of fermions to the three-dimensional noncommutative model: minimal and supersymmetric extensions
We consider the coupling of fermions to the three-dimensional noncommutative
model. In the case of minimal coupling, although the infrared
behavior of the gauge sector is improved, there are dangerous (quadratic)
infrared divergences in the corrections to the two point vertex function of the
scalar field. However, using superfield techniques we prove that the
supersymmetric version of this model with ``antisymmetrized'' coupling of the
Lagrange multiplier field is renormalizable up to the first order in
. The auxiliary spinor gauge field acquires a nontrivial
(nonlocal) dynamics with a generation of Maxwell and Chern-Simons
noncommutative terms in the effective action. Up to the 1/N order all
divergences are only logarithimic so that the model is free from nonintegrable
infrared singularities.Comment: Minor corrections in the text and modifications in the list of
reference
Hilbert Space of Isomorphic Representations of Bosonized Chiral
We analyse the Hilbert space structure of the isomorphic gauge non-invariant
and gauge invariant bosonized formulations of chiral for the particular
case of the Jackiw-Rajaraman parameter . The BRST subsidiary conditions
are found not to provide a sufficient criterium for defining physical states in
the Hilbert space and additional superselection rules must to be taken into
account. We examine the effect of the use of a redundant field algebra in
deriving basic properties of the model. We also discuss the constraint
structure of the gauge invariant formulation and show that the only primary
constraints are of first class.Comment: LaTeX, 19 page
The noncommutative degenerate electron gas
The quantum dynamics of nonrelativistic single particle systems involving
noncommutative coordinates, usually referred to as noncommutative quantum
mechanics, has lately been the object of several investigations. In this note
we pursue these studies for the case of multi-particle systems. We use as a
prototype the degenerate electron gas whose dynamics is well known in the
commutative limit. Our central aim here is to understand qualitatively, rather
than quantitatively, the main modifications induced by the presence of
noncommutative coordinates. We shall first see that the noncommutativity
modifies the exchange correlation energy while preserving the electric
neutrality of the model. By employing time-independent perturbation theory
together with the Seiberg-Witten map we show, afterwards, that the ionization
potential is modified by the noncommutativity. It also turns out that the
noncommutative parameter acts as a reference temperature. Hence, the
noncommutativity lifts the degeneracy of the zero temperature electron gas.Comment: 11 pages, to appear in J. Phys. A: Math. Ge
Chiral bosons and improper constraints
We argue that a consistent quantization of the Floreanini-Jackiw model, as a
constrained system, should start by recognizing the improper nature of the
constraints. Then each boundary conditon defines a problem which must be
treated sparately. The model is settled on a compact domain which allows for a
discrete formulation of the dynamics; thus, avoiding the mixing of local with
collective coordinates. For periodic boundary conditions the model turns out to
be a gauge theory whose gauge invariant sector contains only chiral
excitations. For antiperiodoc boundary conditions, the mode is a second-class
theory where the excitations are also chiral. In both cases, the equal-time
algebra of the quantum energy-momentum densities is a Virasoro algebra. The
Poincar\'e symmetry holds for the finite as well as for the infinite domain.Comment: 13 pages, Revtex file, IF.UFRGS Preprin
Noncommutative quantum mechanics as a gauge theory
The classical counterpart of noncommutative quantum mechanics is a
constrained system containing only second class constraints. The embedding
procedure formulated by Batalin, Fradkin and Tyutin (BFT) enables one to
transform this system into an Abelian gauge theory exhibiting only first class
constraints. The appropriateness of the BFT embedding, as implemented in this
work, is verified by showing that there exists a one to one mapping linking the
second class model with the gauge invariant sector of the gauge theory. As is
known, the functional quantization of a gauge theory calls for the elimination
of its gauge freedom. Then, we have at our disposal an infinite set of
alternative descriptions for noncommutative quantum mechanics, one for each
gauge. We study the relevant features of this infinite set of correspondences.
The functional quantization of the gauge theory is explicitly performed for two
gauges and the results compared with that corresponding to the second class
system. Within the operator framework the gauge theory is quantized by using
Dirac's method.Comment: Accepted for publication in Physical Review
On Duality in the Born-Infeld Theory
The duality symmetric action for the Born-Infeld theory in terms of
two potentials, coupled with non-trivial backgroud fields in four dimensions is
established. This construction is carried out in detail by analysing the
hamiltonian structure of the Born-Infeld theory. The equivalence with the usual
Born-Infeld theory is shown.Comment: revtex, 4 page
Biological Control of the Chagas Disease Vector Triatoma infestans with the Entomopathogenic Fungus Beauveria bassiana Combined with an Aggregation Cue: Field, Laboratory and Mathematical Modeling Assessment
Background: Current Chagas disease vector control strategies, based on chemical insecticide spraying, are growingly threatened by the emergence of pyrethroid-resistant Triatoma infestans populations in the Gran Chaco region of South America. Methodology and findings: We have already shown that the entomopathogenic fungus Beauveria bassiana has the ability to breach the insect cuticle and is effective both against pyrethroid-susceptible and pyrethroid-resistant T. infestans, in laboratory as well as field assays. It is also known that T. infestans cuticle lipids play a major role as contact aggregation pheromones. We estimated the effectiveness of pheromonebased infection boxes containing B. bassiana spores to kill indoor bugs, and its effect on the vector population dynamics. Laboratory assays were performed to estimate the effect of fungal infection on female reproductive parameters. The effect of insect exuviae as an aggregation signal in the performance of the infection boxes was estimated both in the laboratory and in the field. We developed a stage-specific matrix model of T. infestans to describe the fungal infection effects on insect population dynamics, and to analyze the performance of the biopesticide device in vector biological control. Conclusions: The pheromone-containing infective box is a promising new tool against indoor populations of this Chagas disease vector, with the number of boxes per house being the main driver of the reduction of the total domestic bug population. This ecologically safe approach is the first proven alternative to chemical insecticides in the control of T. infestans. The advantageous reduction in vector population by delayedaction fungal biopesticides in a contained environment is here shown supported by mathematical modeling.Fil: Forlani, Lucas. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de Investigaciones BioquĂmicas de La Plata ; ArgentinaFil: Pedrini, NicolĂĄs. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de Investigaciones BioquĂmicas de La Plata ; ArgentinaFil: Girotti, Juan Roberto. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de Investigaciones BioquĂmicas de La Plata ; ArgentinaFil: Mijailovsky, Sergio Javier. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de Investigaciones BioquĂmicas de La Plata ; ArgentinaFil: Cardozo, RubĂ©n Marino. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Salta. Instituto de PatologĂa Experimental. Universidad Nacional de Salta. Facultad de Ciencias de la Salud. Instituto de PatologĂa Experimental; Argentina. Provincia de Salta. Ministerio de Salud PĂșblica. CoordinaciĂłn de GestiĂłn EpidemiolĂłgica; ArgentinaFil: Gentile, Alberto G.. Provincia de Salta. Ministerio de Salud PĂșblica. CoordinaciĂłn de GestiĂłn EpidemiolĂłgica; ArgentinaFil: HernĂĄndez SuĂĄrez, Carlos. Universidad de Colima. Facultad de Ciencias; MĂ©xicoFil: Rabinovich, Jorge Eduardo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Centro de Estudios ParasitolĂłgicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios ParasitolĂłgicos y de Vectores; ArgentinaFil: Juarez, Marta Patricia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de Investigaciones BioquĂmicas de La Plata ; Argentin
Path Integral Approach to Residual Gauge Fixing
In this paper we study the question of residual gauge fixing in the path
integral approach for a general class of axial-type gauges including the
light-cone gauge. We show that the two cases -- axial-type gauges and the
light-cone gauge -- lead to very different structures for the explicit forms of
the propagator. In the case of the axial-type gauges, fixing the residual
symmetry determines the propagator of the theory completely. On the other hand,
in the light-cone gauge there is still a prescription dependence even after
fixing the residual gauge symmetry, which is related to the existence of an
underlying global symmetry.Comment: revtex 13pages, slightly expanded discussion, version to be published
in Physical Review
The Noncommutative Supersymmetric Nonlinear Sigma Model
We show that the noncommutativity of space-time destroys the
renormalizability of the 1/N expansion of the O(N) Gross-Neveu model. A similar
statement holds for the noncommutative nonlinear sigma model. However, we show
that, up to the subleading order in 1/N expansion, the noncommutative
supersymmetric O(N) nonlinear sigma model becomes renormalizable in D=3. We
also show that dynamical mass generation is restored and there is no
catastrophic UV/IR mixing. Unlike the commutative case, we find that the
Lagrange multiplier fields, which enforce the supersymmetric constraints, are
also renormalized. For D=2 the divergence of the four point function of the
basic scalar field, which in D=3 is absent, cannot be eliminated by means of a
counterterm having the structure of a Moyal product.Comment: 15 pages, 7 figures, revtex, minor modifications in the text,
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