Massless Vector Bosons Research Articles

Real-time T≠0 computations in string theory

Introducing an “improved” integral representation for the real-time T≠0 space-time propagator of string theory, we develop a straightforward computational algorithm enabling us to obtain closed-form expressions for any finite temperature quantities from the knowledge of the zero temperature ones and which are also suitable for regularization. All calculations follow the same series of standard steps. As practical examples, we recalculate the closed bosonic string free energy and obtain a closed-form expression for the massless vector boson self-energy of the bosonic open string in the one-loop approximation.

Dynamical mass generation mechanism in the lattice U(1)-Higgs model

We report analytical and numerical evidence for the spontaneous breaking of a residual global gauge symmetry in the U(1)-Higgs model. We also show that, otherwise, the spectrum of the model would have both massless vector and scalar bosons.

Interaction quasipotential for spinor and scalar particles

The two-time Green functions and corresponding quasipotentials for the system of two relativistic particles with spins 0 and 1/2, interacting through exchange of a massless vector boson and a massive scalar boson, are calculated. The calculations are performed using the covariant single-time method of Logunov and Tavkhelidze in the second order of perturbation theory. The dependence of these quantities on the total energy of the system is given. It is shown that, despite a nonlocal form of the quasipotentials, the three-dimensional equations for the wavefunctions can be reduced to the one-dimensional equations using the partial wave decomposition.

The spin structure construction of string models and multi-loop modular invariance

Some properties of the spin structure construction of consistent fermionic string models in ten or fewer dimensions are discussed. In models constructed from free complex world-sheet fermions it is shown that, assuming factorization of amplitudes and one-loop modular invariance, the requirements of a physically sensible projection of states and multi-loop modular invariance are entirely equivalent. The case of models requiring real (rather than complex) fermions for their construction is given a more thorough treatment here. In particular some subleties involved in studying higher-lopp amplitudes are noted and the necessity of some requirements which have appeared in the literature are questioned. A proof that the massless vector bosons appearing in these models fall in the adjoint representation of a Lie group is given, along with some examples of models requiring real fermions for their construction.

Non-abelian gauge bosons in the compactified bosonic membrane theory

We consider the bosonic membrane compactified on a torus. The membrane motion is stabilized by a topologically non-trivial background. We find that, in the narrow membrane limit, the mass formula to O(ħ;) reduces to exactly the same form as that of the compactified closed bosonic string theory, and we obtain (almost) massless vector bosons in the adjoint representation of a simply laced Lie group in D = 27. This is only dimension at which the gravitation and gauge bosons may coexist in that background.

Confinement and vacuum structure in compact QED on the lattice

Using an effective action and assuming that the physical ground state has no structure, we demonstrate that the spectrum of the compact U(1) gauge model has massless (vector and scalar) bosons.

Nearly massless vector bosons as preon-antipreon bound states in a spinor field model

In a composite model which contains as elementary particles only spin-1/2 fermions we investigate in a certain approximation, which does not lean on perturbation theory, theJP=1− preon-antipreon bound states. We find that for a suitable choice of the coupling constant these states are nearly massless if they are highly concentrated.

Symmetry breaking in Kaluza-Klein theories

A new mechanism of symmetry breaking in Kaluza-Klein theories with elementary gauge fields is proposed. In order to implement it, a multiplet of scalar fields with a potential term (as in the usual Higgs mechanism in four dimensions) must be introduced. A general solution of the classical equations of motion is given with the internal manifold being a deformed N-sphere with isometry O(N). The particular six-dimensional case (deformed S2) is discussed in detail. It is shown that in the lowest order of perturbation theory in the deformation parameter epsilon the solution can be made classically stable. The local O(3)*U(1) gauge symmetry is broken to a U(1) subgroup of O(3) and there is a corresponding massless vector boson. The remaining vector bosons acquire small masses of order epsilon 2.

New Coulomb-like gauge for massive gauge fields

The gauge independent renormalization prescription obtained from on-shell scattering of superheavy test particles is extended to the case of spontaneously broken gauge theories. We are led to a generalized Coulomb gauge for massive gauge fields implying the same simple Ward identity for the Coulomb gluon vertex as in the case of massless vector bosons. The derivation of this Ward identity will be simplified considerably by observing a parallel to the method of background field gauges. Gauge independent threshold effects of the β-function are illustrated in an SU(2) model.

Local duality invariance of Maxwell equations

It is shown that the gauge-particle associated with local-duality transformation of Maxwell electro-magnetic equations is a massless axial vector boson which mediates universal long-range interaction between spins. Possible existence of a pure gauge field of this type in an inhomogeneous magneto-electric material is examined.

Interacting quantum fields in a nonsingular cosmological model

Abstract The density of massless vector bosons created in a conformally flat nonsingular cosmological model is calculated.

Dual models for non-hadrons

The possibility of describing particles other than hadrons (leptons, photons, gauge bosons, gravitons, etc.) by a dual model is explored. The Virasoro-Shapiro model is studied first, interpreting the massless spin-two state of the model as a graviton. We prove that in the limit of zero slope (with g vs 2 α′ held fixed) one obtains the Einstein theory of gravitation accompanied by a massless scalar field. Next, the Veneziano model is studied for small slope as an expansion in powers of α′. It is known from previous work that the zeroth order term is precisely the Yang-Mills theory of a multiplet of massless vector bosons. We show that there are order α′ terms arising both from the dual tree and loop graphs. The former constitutes a relatively unimportant modification of the Yang-Mills theory, whereas the latter involves the coupling of the massless scalar and graviton states of the Virasoro-Shapiro model. Thus one may take the point of view that gravity arises as a unitarization effect in a dual unified theory of electromagnetism and weak interactions. In order to obtain the correct values for the electric charge and Newton's constant it is necessary that α′ − 10 −34 GeV −2 The coupling of massless scalar states is also studied.

Equivalence Between Four-Fermion and Yukawa Coupling, and theZ3=0Condition for Composite Bosons

The principal objective of the present work is the derivation of conditions for equivalence (A) between a four-Fermi theory with pseudoscalar coupling and a Yukawa theory with pseudoscalar bosons, and (B) in the corresponding vector case. In general, two conditions are found to be both necessary and sufficient. The first is a condition for the existence of an appropriate boson bound state in the four-Fermi theory. The second condition is that the boson wave function renormalization constant ${Z}_{3}$ in the Yukawa theory be equal to zero. We first derive our results by consideration of fermion-fermion scattering in the chain approximation, and proceed afterwards to prove them valid to all orders in perturbation theory. We also discuss the degenerate vacuum theories of Nambu and Jona-Lasinio and of Bjorken in the chain approximation. In each of these four-Fermi theories, the existence of boson bound states (massless pseudoscalar and massive scalar bosons in the former case, massless vector bosons in the latter) follows automatically from self-consistency conditions. Hence to have equivalence to Yukawa theories in which the bosons are described by elementary fields, we need only impose the ${Z}_{3}=0$ conditions on the Yukawa theories. Finally, we comment on Birula's theory of quantum electrodynamics without electromagnetic field. It is to be stressed that we deal throughout with full-scale relativistic field theories of physical consequence.