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B. M. Pimentel

Publications and source records attributed to B. M. Pimentel.

At least 91 records · Page 5Linked to original sources
arXiv2003

Bose-Einstein Condensation and Free DKP field

The thermodynamical partition function of the Duffin-Kemmer-Petiau theory is evaluated using the imaginary-time formalism of quantum field theory at finite temperature and path integral methods. The DKP partition function displays two features: (i) full equivalence with the partition function for charged scalar particles and charged massive spin 1 particles; and (ii) the zero mode sector which is essential to reproduce the well-known relativistic Bose-Einstein condensation for both theories.

hep-th↗
arXiv2003

Equivalence of Many-Photon Green Functions in DKP and KGF Statistical Quantum Field Theories

We prove the equivalence of many-photon Green functions in statistical quantum field Duffin-Kemmer-Petiau (DKP) and Klein-Gordon-Fock (KGF) theories using functional path integral formalism for partition functional in statistical quantum (finite temperature) field theory. We also calculate the polarization operators in these theories in one-loop approximation, and demonstrate their coincidence.

hep-th↗
arXiv2003

Field gauge divergences in the light-front

The Bethe-Salpeter equation for ground state of two fermions exchanging a gauge boson presents divergences. We used a prescription that allowed an apropriate prescription of the singularity in the boson propagator.

nucl-th↗
arXiv2003

Massless DKP fields in Riemann-Cartan space-times

We study massless Duffin-Kemmer-Petiau (DKP) fields in the context of Einstein-Cartan gravitation theory, interacting via minimal coupling procedure. In the case of an identically vanishing torsion (Riemannian space-times) we show that there exists local gauge symmetries which reproduce the usual gauge symmetries for the massless scalar and electromagnetic fields. On the other hand, similarly to what happens with the Maxwell theory, a non-vanishing torsion, in general, breaks the usual U(1) local gauge symmetry of the electromagnetic field or, in a different point of view, impose conditions on the torsion.

gr-qc↗
arXiv2003

Quantum State Density and Critical Temperature in M-theory

We discuss the asymptotic properties of quantum states density for fundamental $p-$branes which can yield a microscopic interpretation of the thermodynamic quantities in M-theory. The matching of BPS part of spectrum for superstring and supermembrane gives the possibility of getting membrane's results via string calculations. In the weak coupling limit of M-theory the critical behavior coincides with the first order phase transition in standard string theory at temperature less than the Hagedorn's temperature $T_H$. The critical temperature at large coupling constant is computed by considering M-theory on manifold with topology ${\mathbb R}^9\otimes{mathbb T}^2$. Alternatively we argue that any finite temperature can be introduced in the framework of membrane thermodynamics.

hep-th↗
arXiv2002

Spin 1 fields in Riemann-Cartan space-times "via" Duffin-Kemmer-Petiau theory

We consider massive spin 1 fields, in Riemann-Cartan space-times, described by Duffin-Kemmer-Petiau theory. We show that this approach induces a coupling between the spin 1 field and the space-time torsion which breaks the usual equivalence with the Proca theory, but that such equivalence is preserved in the context of the Teleparallel Equivalent of General Relativity.

gr-qc↗
arXiv2002

Interacting spin 0 fields with torsion via Duffin-Kemmer-Petiau theory

Here we study the behaviour of spin 0 sector of the DKP field in spaces with torsion. First we show that in a Riemann-Cartan manifold the DKP field presents an interaction with torsion when minimal coupling is performed, contrary to the behaviour of the KG field, a result that breaks the usual equivalence between the DKP and the KG fields. Next we analyse the case of Teleparallel Equivalent of General Relativity Weitzenbock manifold, showing that in this case there is a perfect agreement between KG and DKP fields. The origins of both results are also discussed.

gr-qc↗
arXiv2001

Thermodynamic Properties of the Relativistic Composite String - Expository Remarks

The Casimir energy for the transverse oscillations of a piecewise uniform closed string is calculated. The great adaptability of this string model with respect to various regularization methods is pointed out. We survey several regularization methods: the cutoff method, the complex contour integration method, and the zeta-function method. The most powerful method in the present case is the contour integration method. The Casimir energy turns out to be negative, and more so the larger is the number of pieces in the string. The thermodynamic free energy and the critical Hagedorn temperature are calculated for a two-piece string. Mass and decay spectra are calculated for quantum massive excitations and the physical meaning of the critical temperatures characterizing the radiation in the decay of a massive microstate is discussed.

hep-th↗
arXiv2001

Duffin-Kemmer-Petiau Theory in the Causal Approach

In this paper we consider the scalar sector of Duffin-Kemmer-Petiau theory in the framework of Epstein-Glaser causal method. We calculate the lowest order distributions for Compton scattering, vacuum polarization, self-energy and vertex corrections. By requiring gauge invariance of the theory we recover, in a natural way, the scalar propagator of the usual effective theory.

hep-th↗
arXiv2001

Duffin-Kemmer-Petiau equation in Riemannian space-times

In this work we analyze the generalization of Duffin-Kemmer-Petiau equation to the case of Riemannian space-times and show that the usual results for Klein-Gordon and Proca equations in Riemannian space-times can be fully recovered when one selects, respectively, the spin 0 and 1 sectors of Duffin-Kemmer-Petiau theory.

gr-qc↗
arXiv2000

Duffin-Kemmer-Petiau and Klein-Gordon-Fock Equations for Electromagnetic, Yang-Mills and external Gravitational Field Interactions: proof of equivalence

Starting from Generating functional for Green Function (GF), constracted from Lagrangian action in Duffin-Kemmer-Petiau (DKP) theory (L-approach) we strictly prove that the physical matrix elements of S-matrix in DKP and Klein-Gordon-Fock (KGF) theories coincide in cases of interaction spin O particles with external and quantized Maxwell and Yang-Mills fields and in case of external gravitational field (without or with torsion). For the proof we use reduction formulas of Lehmann Symanzik, Zimmermann (LSZ). We prove that many photons and Yang-Mills particles GF coincide in the both theories, too.

hep-th↗
arXiv2000

Irreducibility and Compositeness in q-Deformed Harmonic Oscillator Algebras

q-Deformed harmonic oscillator algebra for real and root of unity values of the deformation parameter is discussed by using an extension of the number concept proposed by Gauss, namely the Q-numbers. A study of the reducibility of the Fock space representation which explores the properties of the Gauss polynomials is presented. When the deformation parameter is a root of unity, an interesting result comes out in the form of a reducibility scheme for the space representation which is based on the classification of the primitive or non-primitive character of the deformation parameter. An application is carried out for a q-deformed harmonic oscillator Hamiltonian, to which the reducibility scheme is explicitly applied. For finite-dimensional spaces associated to non-primitive roots of unity the compositeness of the k-fermions/quons is discussed.

math.QA↗
arXiv1999

Remarks on Duffin-Kemmer-Petiau theory and gauge invariance

Two problems relative to the electromagnetic coupling of Duffin-Kemmer-Petiau (DKP) theory are discussed: the presence of an anomalous term in the Hamiltonian form of the theory and the apparent difference between the Interaction terms in DKP and Klein-Gordon (KG) Lagrangians. For this, we first discuss the behavior of DKP field and its physical components under gauge transformations. From this analysis, we can show that these problems simply do not exist if one correctly analyses the physical components of DKP field.

hep-th↗
arXiv1999

On Equivalence of Duffin-Kemmer-Petiau and Klein-Gordon Equations

A strict proof of equivalence between Duffin-Kemmer-Petiau (DKP) and Klein-Gordon (KG) theories is presented for physical S-matrix elements in the case of charged scalar particles interacting in minimal way with an external or quantized electromagnetic field. First, Hamiltonian canonical approach to DKP theory is developed in both component and matrix form. The theory is then quantized through the construction of the generating functional for Green functions (GF) and the physical matrix elements of S-matrix are proved to be relativistic invariants. The equivalence between both theories is then proved using the connection between GF and the elements of S-matrix, including the case of only many photons states, and for more general conditions - so called reduction formulas of Lehmann, Symanzik, Zimmermann.

hep-th↗
arXiv1999

Gauged Thirring Model in the Heisenberg Picture

We consider the (2+1)-dimensional gauged Thirring model in the Heisenberg picture. In this context we evaluate the vacuum polarization tensor as well as the corrected gauge boson propagator and address the issues of generation of mass and dynamics for the gauge boson (in the limits of QED$_3$ and Thirring model as a gauge theory, respectively) due to the radiative corrections.

hep-th↗
arXiv1999

Radiative Corrections for the Gauged Thirring Model in Causal Perturbation Theory

We evaluate the one-loop fermion self-energy for the gauged Thirring model in (2+1) dimensions, with one massive fermion flavor, in the framework of the causal perturbation theory. In contrast to QED$_3$, the corresponding two-point function turns out to be infrared finite on the mass shell. Then, by means of a Ward identity, we derive the on-shell vertex correction and discuss the role played by causality for nonrenormalizable theories.

hep-th↗
arXiv1999

Remarks on Infrared Dynamics in QED3

In this work we study how the infrared sector of the interaction Hamiltonian can affect the construction of the S matrix operator of QED in (2+1) dimensions.

hep-th↗