A device to assess the upper limb isometric muscle strength
In this work we project and build an equipment for upper limb muscle strength assessment and we did some assays to measure it from volunteers.
physics.med-ph↗
arXiv subjects
J. H. O. Sales
Publications and source records attributed to J. H. O. Sales.
Plane and parabolic solar panels
We present a plane and parabolic collector that absorbs radiant energy and transforms it in heat. Therefore we have a panel to heat water. We study how to increment this capture of solar beams onto the panel in order to increase its efficiency in heating water.
physics.gen-ph↗
QED$_{4}$ Ward Identity for fermionic field in the light-front
In a covariant gauge we implicitly assume that the Green's function propagates information from one point of the space-time to another, so that the Green's function is responsible for the dynamics of the relativistic particle. In the light front form, which in principle is a change of coordinates, one would expect that this feature would be preserved. In this manner, the fermion's field propagator can be split into a propagating piece and a non-propagating (``contact'') term. Since the latter (``contact'') one does not propagate information, and therefore, assumedly with no harm to the field dynamics we wanted to know what would be the impact of dropping it off. To do that, we investigated its role in the Ward identity in the light front.
hep-th↗
Angular momentum quantization from Planck's energy quantization
We present in this work a pedagogical way of quantizing the atomic orbit for the hydrogen's atom model proposed by Bohr without using his hypothesis of angular momentum quantization. In contrast to the usual treatment for the orbital quantization, we show that using energy conservation, correspondence principle and Plank's energy quantization Bohr's hypothesis can be deduced from and is a consequence of the Planck's energy quantization.
quant-ph↗
Antiparticle Contribution in the Cross Ladder Diagram for Bethe-Salpater Equation in the Light-Front
We construct the homogeneous integral equation for the vertex of the bound state in the light front with the kernel approximated to order g^4. We will truncate the hierarchical equations from Green functions to construct dynamical equations for the two boson bound state exchanging interacting intermediate bosons and including pair creation process contributing to the crossed ladder diagram.
hep-th↗
Revisiting Bohr's quantization hypothesis for the atomic orbitals
We deduce the quantization of the atomic orbit for the hydrogen's atom model proposed by Bohr without using his hypothesis of angular momentum quantization. We show that his hypothesis can be deduced from and is a consequence of the Planck's energy quantization.
physics.atom-ph↗
Iterated Resolvent Function for the Ladder Bethe-Salpeter Equation
We developed the formal connection of the field theoretical Bethe-Salpeter equation including the ladder approximation with its representation on the light-front for a bosonic model. We use the light-front Green's function for the N-particle system for two-particles plus N-2 intermediate bosons. We derived an infinite set of coupled hierarchy equations or iterated resolvent from which the Green's function can be calculated. These equations allow a consistent truncation of the light-front Fock-space. We show explicitly the represention of the covariant two-body T-matrix and bound state vertex in the light-front.
nucl-th↗
Gauge transformations are not canonical transformations
In classical mechanics, we can describe the dynamics of a given system using either the Lagrangian formalism or the Hamiltonian formalism, the choice of either one being determined by whether one wants to deal with a second degree differential equation or a pair of first degree ones. For the former approach, we know that the Euler-Lagrange equation of motion remains invariant under additive total derivative with respect to time of any function of coordinates and time in the Lagrangian function, whereas the latter one is invariant under canonical transformations. In this short paper we address the question whether the transformation that leaves the Euler-Lagrange equation of motion invariant is also a canonical transformation and show that it is not.
hep-th↗
Antiparticle Contribution in the Cross Ladder Diagram for Two Boson Propagation in the Light-front
In the light-front milieu, there is an implicit assumption that the vacuum is trivial. By this " triviality " is meant that the Fock space of solutions for equations of motion is sectorized in two, one of positive energy k- and the other of negative one corresponding respectively to positive and negative momentum k+. It is assumed that only one of the Fock space sector is enough to give a complete description of the solutions, but in this work we consider an example where we demonstrate that both sectors are necessary.
hep-th↗
Why pair production cures covariance in the light-front?
We show that the light-front vaccum is not trivial, and the Fock space for positive energy quanta solutions is not complete. As an example of this non triviality we have calculated the electromagnetic current for scalar bosons in the background field method were the covariance is restored through considering the complete Fock space of solutions. We also show thus that the method of "dislocating the integration pole" is nothing more than a particular case of this, so that such an "ad hoc" prescription can be dispensed altogether if we deal with the whole Fock space. In this work we construct the electromagnetic current operator for a system composed of two free bosons. The technique employed to deduce these operators is through the definition of global propagators in the light front when a background electromagnetic field acts on one of the particles.
hep-th↗
Is the Bohr's quantization hypothesis necessary ?
We deduce the quantization of Bohr's hydrogen's atomic orbit without using his hypothesis of angular momentum quantization. We show that his hypothesis is nothing more than a consequence of the Planck's energy quantization.
physics.ed-ph↗
Singularity-softening prescription for the Bethe-Salpeter equation
The reduction of the two fermion Bethe-Salpeter equation in the framework of light-front dynamics is studied for one gauge A+=0. The arising effective interaction can be perturbatively expanded in powers of the coupling constant g, allowing a defined number of gauge boson exchanges. The singularity of the kernel of the integral equation at vanishs plus momentum of the gauge is canceled exactly in on approuch. We studied the problem using a singularity-softening prescription for the light-front gauge.
hep-th↗
The Light Front Gauge Propagator: The Status Quo
At the classical level, the inverse differential operator for the quadratic term in the gauge field Lagrangian density fixed in the light front through the multiplier (nA)^2 yields the standard two term propagator with single unphysical pole of the type (kn)^-1. Upon canonical quantization on the light-front, there emerges a third term of the form (kn^(mu)n^(nu))(kn)^-2. This third term in the propagator has traditionally been dropped on the grounds that is exactly cancelled by the "instantaneous" term in the interaction Hamiltonian in the light-front. Our aim in this work is not to discuss which of the propagators is the correct one, but rather to present at the classical level, the gauge fixing conditions that can lead to the three-term propagator.
hep-th↗
Light-front gauge propagator
Gauge fields are special in the sense that they are invariant under gauge transformations and they lead to problems when we try quantizing them straightforwardly. To circumvent this problem we need to specify a gauge condition to fix gauge.
nucl-th↗
Light-front time picture of the Bethe-Salpeter equation fermionic
The reduction of the equation of Bethe-Salpeter of two fermions in front of light is studied for the Yukawa model. We use the light-front Green's function for the N-particle system for two-fermions plus N-2 intermediate bosons.
hep-th↗
Can two or more gauge bosons propagate in the light-front?
Gauge fields in the light-front are usually fixed via the nA=0 condition yielding the non-local singularities of the type (kn)^(-a)=0 and a=1,2,.. in the gauge boson propagator which must be addressed conveniently. In calculating this propagator for n noncovariant gauge bosons those non-local terms demand the use of a prescription to ensure causality. We show that from 2 gauge bosons onward the implementation of such a prescription does not remove certain pathologies such as the non existence of two or more free propagating gauge bosons in the light-front form.
hep-th↗
Relativistic free-particle quantization on the light-front: New aspects
We use the light-front machinery to study the behavior of a relativistic free particle and obtain the quantum commutation relations from the classical Poisson brackets. We argue that the usual projection onto the light-front coordinates for these from the covariant commutation ralations does not reproduce the expected results.
hep-th↗
Surprises in the relativistic free-particle quantization on the light-front
We use the light front ``machinery'' to study the behavior of a relativistic free particle and obtain the quantum commutation relations from the classical Poisson brackets. We argue that their usual projection onto the light-front coordinates from the covariant commutation relations show that there is an inconsistency in the expected correlation between canonically conjugate variables ``time'' and ``energy''. Moreover we show that this incompatibility originates from the very definition of the Poisson brackets that is employed and present a simple remedy to this problem and envisages a profound physical implication on the whole process of quantization.
hep-th↗