122263475
Three triplets, paraquarks, and ''colored'' quarks
119892209
Finite quantum electrodynamics: A field theory using an indefinite metric
A finite relativistic field theory of quantum electrodynamics is formulated; the theory involves as an essential element the use of an indefinite metric to remove the divergences. Two auxiliary fermion fields with anticommutation relations of opposite sign from the normal fermion field (electron) are coupled with the electron to the electromagnetic field in such a manner that any matrix element, calculated by a perturbation expansion, is finite. Although the new Lagrangian is not explicitly gauge invariant, the electromagnetic field is quantized by a method that yields a propagator in the true Landau gauge, and it is shown that this is sufficient to insure that the physical vector particles are zero-mass transverse quanta (i.e., photons). The physical electron mass and the fine-structure constant are put into the theory, leaving only the masses of the two auxiliary fields as parameters. The effects of mass and charge renormalization are calculated (the former using a technique involving a Taylor expansion in the mass), and are required to be small so that there is no explicit contradiction to the validity of the perturbation expansion. The anomalous magnetic moment of the electron and the differential and total cross sections for Compton scattering are calculated and compared with experiment. A range of the auxiliary mass parameters is found for which the predictions agree with experiment and for which the expansion criteria are satisfied. Thus, a finite quantum electrodynamics is accomplished.
11115006
Environmental adaptability and mutants: Exploring new concepts in particle transport for multi-scale simulation
Ongoing investigations to introduce software techniques suitable to support new experimental requirements for multi-scale simulation are discussed.
121155180
DYON THREE-TRIPLET MODEL OF HADRONS.
118337761
Manifest dyality invariance in electrodynamics and the cabibbo-ferrari theory of magnetic monopoles
SummaryOne of the intrinsic symmetry properties of the Maxwell-Lorentz theory of electrodynamics is the invariance of the theory under « dyality » transformation, that is, a dual transformation on fieldsand sourcessimultaneously. In this paper we give a manifestly dyality-invariant formulation of electrodynamics. This is done by expressing the electromagnetic-field tensors in terms of an antisymmetric tensor of rank two, called a Hertz tensor, consisting of electric and magnetic Hertz vector potentials. An equation is derived which relates the electromagnetic fields when sources consist of electric charges only, magnetic charges only, and both. The present formalism provides a natural physical basis for the Cabibbo-Ferrari theory in which two four-vector potentials and a mixed gauge transformation between them are introduced.RiassuntoUna delle proprietà di simmetria intrinseca della teoria di Maxwell-Lorentz dell’elettrodinamica è l’invarianza della teoria rispetto alle trasformazioni di «dialità», cioè una trasformazione duale sui campie le sorgenticontemporaneamente. In questo articolo si espone una formulazione dell’elettrodinamica che è manifestamente invariante rispetto alla dialità. Si fà ciò esprimendo i tensori del campo elettromagnetico in termini di un tensore antisimmetrico di rango due, detto tensore di Hertz, consistente di potenziali del vettore di Hertz elettrico e magnetico. Si deduce un’equazione che mette in relazione i campi magnetici quando le sorgenti consistono di sole cariche elettriche, di sole cariche magnetiche, o di entrambe. Questo formalismo fornisce una naturale base fisica per la teoria di Cabibbo-Ferrari, in cui si introducono due potenziali quadrivettori e una trasformazione di gauge mista tra essi.РеэюмеОдно иэ свойств внутренней симметрии Максвелл-Лорентцевс кой теории злектродинамики представляет инвариантность теории относительно преобраэования «диальности», т.е. одновременное дуальное преобраэование полей и источников. В зтой статье мы приводим формулировку злектродинамики, обладаюшую явной диальной инвариантностью. Это достигается эа счет выражения тенэора злектромагнитного поля череэ антисимметричный тенэор второго ранга, наэываемый тенэором Герца, который состоит иэ злектрического и магнитного векторных потенциалов Герца. Выводится уравнение, которое свяэывает злектромагнитные поля, когда источники состоят только иэ злектрических эарядов, только иэ магнитных эарядов и тех и других. Предлагаемый формалиэм обеспечивает естественную фиэическую основу для теории Кабиббо-Феррари, в которой вводятся два четырех-векторных потенциала и смещанное калибровочное преобраэование между ними.
123307684
Hadronic regge sequences as primitive realizations of SL(3,R) symmetry☆
Abstract Four primitive infinite dimensional unitary representations of the group of rotations and deformations - SL(3,R) - are constructed and associated with the four Regge trajectories: π, ϱ, N, Δ. The model predicts E2 transition moments and a power law for E versus j consistent with the Chew-Frautschi relation E∼j 1 2 .
119715337
Fundamental structure of loop quantum gravity
In the recent twenty years, loop quantum gravity, a background independent approach to unify general relativity and quantum mechanics, has been widely investigated. The aim of loop quantum gravity is to construct a mathematically rigorous, background independent, non-perturbative quantum theory for a Lorentzian gravitational field on a four-dimensional manifold. In the approach, the principles of quantum mechanics are combined with those of general relativity naturally. Such a combination provides us a picture of, so-called, quantum Riemannian geometry, which is discrete on the fundamental scale. Imposing the quantum constraints in analogy from the classical ones, the quantum dynamics of gravity is being studied as one of the most important issues in loop quantum gravity. On the other hand, the semi-classical analysis is being carried out to test the classical limit of the quantum theory. In this review, the fundamental structure of loop quantum gravity is presented pedagogically. Our main aim is to help ...
16629504
Five-dimensional Brans-Dicke theory and cosmic acceleration
We consider a 5-dimensional scalar-tensor theory which is a direct generalization of the original 4-dimensional Brans-Dicke theory to five dimensions. By assuming that there is a hypersurface-orthogonal spacelike Killing vector field in the underlying 5-dimensional spacetime, the theory is reduced to a 4-dimensional theory where the 4-metric is coupled with two scalar fields. The cosmological implication of this reduced theory is then studied in the Robertson-Walker model. It turns out that the two scalar fields may account naturally for the present accelerated expansion of our universe. The observational restriction of the reduced cosmological model is also analyzed.
119275326
4-dimensional spin-foam model with quantum Lorentz group
We study the quantum group deformation of the Lorentzian EPRL spin-foam model. The construction uses the harmonic analysis on the quantum Lorentz group. We show that the quantum group spin-foam model so defined is free of the infra-red divergence, thus gives a finite partition function on a fixed triangulation. We expect this quantum group spin-foam model is a spin-foam quantization of discrete gravity with a cosmological constant.
119177776
Master constraint operators in loop quantum gravity
Abstract We introduce a master constraint operator M ˆ densely defined in the diffeomorphism invariant Hilbert space in loop quantum gravity, which corresponds classically to the master constraint in the programme. It is shown that M ˆ is positive and symmetric, and hence has its Friedrichs self-adjoint extension. The same conclusion is tenable for an alternative master operator M ˆ ′ , whose quadratic form coincides with the one proposed by Thiemann. So the master constraint programme for loop quantum gravity can be carried out in principle by employing either of the two operators.
118178605
SL(2,C) Chern–Simons theory, a non-planar graph operator, and 4D quantum gravity with a cosmological constant: Semiclassical geometry
Abstract We study the expectation value of a nonplanar Wilson graph operator in SL ( 2 , C ) Chern–Simons theory on S 3 . In particular we analyze its asymptotic behavior in the double-scaling limit in which both the representation labels and the Chern–Simons coupling are taken to be large, but with fixed ratio. When the Wilson graph operator has a specific form, motivated by loop quantum gravity, the critical point equations obtained in this double-scaling limit describe a very specific class of flat connection on the graph complement manifold. We find that flat connections in this class are in correspondence with the geometries of constant curvature 4-simplices. The result is fully non-perturbative from the perspective of the reconstructed geometry. We also show that the asymptotic behavior of the amplitude contains, at the leading order, an oscillatory part proportional to the Regge action for the single 4-simplex in the presence of a cosmological constant. In particular, the cosmological term contains the full-fledged curved volume of the 4-simplex. Interestingly, the volume term stems from the asymptotics of the Chern–Simons action. This can be understood as arising from the relation between Chern–Simons theory on the boundary of a region, and a theory defined by an F 2 action in the bulk. Another peculiarity of our approach is that the sign of the curvature of the reconstructed geometry, and hence of the cosmological constant in the Regge action, is not fixed a priori, but rather emerges semiclassically and dynamically from the solution of the equations of motion. In other words, this work suggests a relation between 4-dimensional loop quantum gravity with a cosmological constant and SL ( 2 , C ) Chern–Simons theory in 3 dimensions with knotted graph defects.