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J. Barcelos-Neto

Publications and source records attributed to J. Barcelos-Neto.

At least 19 recordsLinked to original sources
arXiv2003

On the trace anomaly and the energy-momentum conservation of quantum fields at D=2 in classical curved backgrounds

We study the conformal symmetry and the energy-momentum conservation of scalar field interacting with a curved background at D=2. We avoid to incorporate the metric determinant into the measure of the scalar field to explain the conformal anomaly and the consequent energy-momentum conservation. Contrarily, we split the scalar field in two other fields, in such a way that just one of them can be quantized. We show that the same usual geometric quantities of the anomaly are obtained, which are accompanied by terms containing the new field of the theory.

gr-qc↗
arXiv2002

Noncommutative fields in curved space

We consider a noncommutative theory developed in a curved background. We show that the Moyal product has to be conveniently modified and, consequently, some of its old properties are lost compared with the flat case. We also address the question of diffeomorphism symmetry.

hep-th↗
arXiv2002

Statistical transmutation of quantum bosonic strings coupled to general four-dimensional Chern-Simons theory

A bosonic string coupled to the generalized Chern-Simons theory in 3+1D acquires a magnetic field along itself, when it is closed, and a topological charge at its extremity, when it is open. We construct the creation operators for the full quantum field states associated to these strings and determine the dual algebra satisfied by them. We show that the creation operator fo the composite state of a quantum closed bosonic string, bearing a magnetic flux, and a topologically charged open bosonic string, possesses generalized statistics. The relation of our results with previous approaches to the problem is also established.

hep-th↗
arXiv2002

A new sequence for topological terms at any spacetime dimensions

We investigate a sequence of quadratic topological terms of the Chern-Simons type in different spacetime dimensions, related by dimensional compactification and sharing the properties of topological mass generation and statistical transmutation. The implications for bosonization in several dimensions are also analyzed.

hep-th↗
arXiv2001

Compactification of gauge theories and the gauge invariance of massive modes

We study the gauge invariance of the massive modes in the compactification of gauge theories from D=5 to D=4. We deal with Abelian gauge theories of rank one and two, and with non-Abelian ones of rank one. We show that Stückelberg fields naturally appear in the compactification mechanism, contrarily to what usually occurs in literature where they are introduced by hand, as a trick, to render gauge invariance for massive theories. We also show that in the non-Abelian case they appear in a very different way when compared with their usual implementation in the non-Abelian Proca model.

hep-th↗
arXiv2001

Remarks on the canonical quantization of noncommutative theories

Free noncommutative fields constitute a natural and interesting example of constrained theories with higher derivatives. The quantization methods involving constraints in the higher derivative formalism can be nicely applied to these systems. We study real and complex free noncommutative scalar fields where momenta have an infinite number of terms. We show that these expressions can be summed in a closed way and lead to a set of Dirac brackets which matches the usual corresponding brackets of the commutative case.

hep-th↗
arXiv2001

A model for time-dependent cosmological constant

We present a model for a spacetime dependent cosmological {\it constant}. We make a realization of this model based on a possible quantum aspects of the initial stage of the universe and relate the cosmological constant with the chiral anomaly.

hep-th↗
arXiv2001

Hamiltonian embedding of the massive noncommutative U(1) theory

We show that the massive noncommutative U(1) can be embedded in a gauge theory by using the BFFT Hamiltonian formalism. By virtue of the peculiar non-Abelian algebraic structure of the noncommutative massive U(1) theory, several specific identities involving Moyal commutators had to be used in order to make the embedding possible. This leads to an infinite number of steps in the iterative process of obtaining first-class constraints. We also shown that the involutive Hamiltonian can be constructed.

hep-th↗
arXiv2000

Spontaneous compactification of D=5 two-form gauge fields and the obtainment of Maxwell and Yang-Mills theories

We show that the spontaneous compactification of the Abelian and non-Abelian two-form gauge field theories from $D=4+1$ to $D=3+1$ leads to the same theories plus the Maxwell and Yang-Mills ones, respectively. The vector potential comes from the zero mode of the fifth component of the tensor gauge field in D=5. Concerning to the non-Abelian case, it is necessary to make a more refined definition of the three-form stress tensor in order to be compatible, after the compactification, with the two-form stress tensor of the Yang-Mills theory.

hep-th↗
arXiv2000

Partially embedding of the quantum mechanical analog of the nonlinear sigma model

We consider the quantum mechanical analog of the nonlinear sigma model. There are difficulties to completely embed this theory by directly using the Batalin, Fradkin, Fradkina, and Tyutin (BFFT) formalism. We show in this paper how the BFFT method can be conveniently adapted in order to achieve a gauge theory that partially embeds the model.

hep-th↗
arXiv1999

Dispersionless Fermionic KdV

We analyze the dispersionless limits of the Kupershmidt equation, the SUSY KdV-B equation and the SUSY KdV equation. We present the Lax description for each of these models and bring out various properties associated with them as well as discuss open questions that need to be addressed in connection with these models.

solv-int↗
arXiv1999

Extended supersymmetry in D=1+1

We extend superspace by introducing an antisymmetric tensorial coordinate. The resulting theory presents a supersymmetry with central charge. After integrating over the tensorial coordinate, an effective action describing massive bosons and fermions is explicitely derived for the spacetime dimension D=2. The adopted procedure is simpler than the Kaluza-Klein one and can suggest an alternative for string compactifications.

hep-th↗
arXiv1999

Functional versus canonical quantization of a nonlocal massive vector-gauge theory

It has been shown in literature that a possible mechanism of mass generation for gauge fields is through a topological coupling of vector and tensor fields. After integrating over the tensor degrees of freedom, one arrives at an effective massive theory that, although gauge invariant, is nonlocal. Here we quantize this nonlocal resulting theory both by path integral and canonical procedures. This system can be considered as equivalent to one with an infinite number of time derivatives and consequently an infinite number of momenta. This means that the use of the canonical formalism deserves some care. We show the consistency of the formalism we use in the canonical procedure by showing that the obtained propagators are the same as those of the (Lagrangian) path integral approach. The problem of nonlocality appears in the obtainment of the spectrum of the theory. This fact becomes very transparent when we list the infinite number of commutators involving the fields and their velocities.

hep-th↗