Pure spinor partition function and the massive superstring spectrum

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

On semiclassical analysis of pure spinor superstring in an AdS(5) x S-5 background

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Energy spectrum and eigenfunctions through the Quantum Section Method

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of Ionic Liquid on the Determination of Aromatic Amines as Contaminants in Hair Dyes by Liquid Chromatography Coupled to Electrochemical Detection

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

HIGHER-DERIVATIVE SCHWINGER MODEL

Using the operator formalism, we obtain the bosonic representation for the free fermion field satisfying an equation of motion with higher-order derivatives. Then, we consider the operator solution of a generalized Schwinger model with higher-derivative coupling. Since the increasing of the derivative order implies the introduction of an equivalent number of extra fermionic degrees of freedom, the mass acquired by the gauge field is bigger than the one for the standard two-dimensional QED. An analysis of the problem from the functional integration point of view corroborates the findings of canonical quantization, and corrects certain results previously announced in the literature on the basis of Fujikawa's technique.

Multiloop superstring amplitudes from non-minimal pure spinor formalism

Using the non-minimal version of the pure spinor formalism, manifestly super-Poincare covariant superstring scattering amplitudes can be computed as in topological string theory without the need of picture-changing operators. The only subtlety comes from regularizing the functional integral over the pure spinor ghosts. In this paper, it is shown how to regularize this functional integral in a BRST-invariant manner, allowing the computation of arbitrary multiloop amplitudes. The regularization method simplifies for scattering amplitudes which contribute to ten-dimensional F-terms, i.e. terms in the ten-dimensional superspace action which do not involve integration over the maximum number of theta's.

Casimir effect for the scalar field under Robin boundary conditions: a functional integral approach

In this work we show how to define the action of a scalar field such that the Robin boundary condition is implemented dynamically, i.e. as a consequence of the stationary action principle. We discuss the quantization of that system via functional integration. Using this formalism, we derive an expression for the Casimir energy of a massless scalar field under Robin boundary conditions on a pair of parallel plates, characterized by constants c(1) and c(2). Some special cases are discussed; in particular, we show that for some values of cl and c(2) the Casimir energy as a function of the distance between the plates presents a minimum. We also discuss the renormalization at one-loop order of the two-point Green function in the philambda(4) theory subject to the Robin boundary condition on a plate.

PATH INTEGRAL AND OPERATOR APPROACH FOR THE PODOLSKY-SCHWINGER MODEL

We study the role of the thachyonic excitation which emerges from the quantum electrodynamics in two dimensions with Podolsky term. The quantization is performed by using path integral framework and the operator approach.

Comments on spin operators and spin-polarization states of 2+1 fermions

In this brief article we discuss spin-polarization operators and spin-polarization states of 2 + 1 massive Dirac fermions and find a convenient representation by the help of 4-spinors for their description. We stress that in particular the use of such a representation allows us to introduce the conserved covariant spin operator in the 2 + 1 field theory. Another advantage of this representation is related to the pseudoclassical limit of the theory. Indeed, quantization of the pseudoclassical model of a spinning particle in 2 + 1 dimensions leads to the 4-spinor representation as the adequate realization of the operator algebra, where the corresponding operator of a first-class constraint, which cannot be gauged out by imposing the gauge condition, is just the covariant operator previously introduced in the quantum theory.

Ordering ambiguity versus representation

In this work we show that the ordering ambiguity on quantization depends on the representation choice. This property is then used to solve unambiguously some particular systems. Finally, we speculate on the consequences for more involved cases.

The SU(2) Skyrme model and anomaly

The SU(2) Shyrme model, expanding in the collective coordinates variables, gives rise to second-class constraints. Recently this system was embedded in a more general Abelian gauge theory using the BFFT Hamiltonian method. in this work we quantize this gauge theory computing the Noether current anomaly using for this two different methods: an operatorial Dirac first class formalism and the non-local BV quantization coupled with the Fujikawa regularization procedure. (C) 2000 Elsevier B.V. B.V. All rights reserved.

Further on the current algebra of WZNW models at and away from criticality

We comment on the off-critical perturbations of WZNW models by a mass term as well as by another descendent operator, when we can compare the results with further algebra obtained from the Dirac quantization of the model, in such a way that a more general class of models be included. We discover, in both cases, hidden Kac-Moody algebras obeyed by some currents in the off-critical case, which in several cases are enough to completely fix the correlation functions.

Non-anomalous generalized chiral Schwinger model

Recently, Basseto and Griguolo1 did a perturbative quantization of what they called a generalized chiral Schwinger model. As a consequence of the kind of quantization adopted, some gauge-dependent masses raised in the model. On the other hand, we discussed the possibility of introducing a generalized Wess-Zumino term,2 where such gauge-dependent masses did appear. Here we intend to show that one can construct a non-anomalous version of a model which include that, presented by Basseto and Griguolo as a particular case, by adding to it a generalized Wess-Zumino term, as proposed in Ref. 2. So we conclude that it is possible to construct a gauge-invariant extension of the model quoted in Ref. 1, and this can be done through a Wess-Zumino term of the type proposed in Ref. 2.

On the picture dependence of Ramond-Ramond cohomology

Closed string physical states are BRST cohomology classes computed on the space of states annihilated by b- 0. Since b- 0 does not commute with the operations of picture changing, BRST cohomologies at different pictures need not agree. We show explicitly that Ramond-Ramond (RR) zero-momentum physical states are inequivalent at different pictures, and prove that non-zero-momentum physical states are equivalent in all pictures. We find that D-brane states represent BRST classes that are non-polynomial on the superghost zero-modes, while RR gauge fields appear as polynomial BRST classes. We also prove that in x-cohomology, the cohomology where the zero-mode of the spatial coordinates is included, there is a unique ghost-number one BRST class responsible for the Green-Schwarz anomaly, and a unique ghost number minus one BRST class associated with RR charge. © 1998 Elsevier Science B.V.

Conformai field theory of AdS background with Ramond-Ramond flux

We review a formalism of superstring quantization with manifest six-dimensional spacetime supersymmetry, and apply it to AdS3 × S3 backgrounds with Ramond-Ramond flux. The resulting description is a conformal field theory based on a sigma model whose target space is a certain supergroup SU′(2|2).