arXiv subjects

Douglas Singleton

Publications and source records attributed to Douglas Singleton.

At least 109 records · Page 6Linked to original sources

arXiv2006

Fermion generations, masses and mixings in a 6D brane model

We study the motion of higher dimensional fermions in a non-singular 6D brane background with an increasing warp factor. This background acts as a potential well trapping fermions and fields of other spins near a 3+1 dimensional brane. By adjusting the shape of this potential well it is possible to obtain three normalizable zero mass modes giving a possible higher dimensional solution to the fermion generation puzzle. The three different zero mass modes correspond to the different angular momentum eigenvalues for rotations around the brane. This bulk angular momentum acts as the family or generation number. The three normalizable zero modes have different profiles with respect to the bulk, thus by coupling the higher dimensional fermion field to a higher dimensional scalar field it is possible to generate both a realistic mass hierarchy and realistic mixings between the different families.

hep-th↗

arXiv2005

Fermion generations on a co-dimension 2 brane

We examine the behavior of fermions in the presence of a non-singular thick brane having co-dimension 2. It is shown that one can obtain three trapped zero modes which differ from each other by having different values of angular momentum with respect to the 2 extra dimensions. These three zero modes are located at different points in the extra dimensional space and are interpreted as the three generations of fundamental fermions. The angular momentum in the extra dimensions (which is not conserved) acts as the family or generation label. This gives a higher dimensional picture for the family puzzle.

hep-th↗

arXiv2004

Nonperturbative calculations in SU(3) gauge theory

An approximate technique for performing nonperturbative calculations in quantum SU(3) gauge theory is presented. One aspect of this nonperturbative method is the breaking down $SU(3) \to SU(2) + coset$. The procedure also uses some aspects of an old method by Heisenberg to calculate the n-point Green's function of strongly interacting, non-linear fields. Using these ideas we give approximate calculations of the 2 and 4-points Green's functions.

hep-ph↗

arXiv2004

Gauge procedure with gauge fields of various ranks

The standard procedure for making a global phase symmetry local involves the introduction of a rank 1, vector field in the definition of the covariant derivative. Here it is shown that it is possible to gauge a phase symmetry using fields of various ranks. In contrast to other formulations of higher rank gauge fields we begin with the coupling of the gauge field to some matter field, and then derive the gauge invariant, field strength tensor. Some of these gauge theories are similar to general relativity in that their covariant derivatives involve derivatives of the rank n gauge field rather than just the gauge field. For general relativity the covariant derivative involves the Christoffel symbols which are written in terms of derivatives of the metric tensor. Many (but not all) of the Lagrangians that we find for these higher rank gauge theories lead to nonrenormalizable quantum theories which is also similar to general relativity.

hep-th↗

arXiv2004

Gravitational trapping potential with arbitrary extra dimensions

We extend a recently discovered, non-singular 6 dimensional brane, solution to D=4+n dimensions. As with the previous 6D solution the present solution provides a gravitational trapping mechanism for fields of spin 0, 1/2, 1 and 2. There is an important distinction between 2 extra dimensions and $n$ extra dimensions that makes this more than a trivial extension. In contrast to gravity in n >2 dimensions, gravity in n=2 dimensions is conformally flat. The stress-energy tensor required by this solution has reasonable physically properties, and for n=2 and n=3 can be made to asymptotically go to zero as one moves away from the brane.

hep-th↗

arXiv2003

Brane in 6D with increasing gravitational trapping potential

A new solution to Einstein equations in (1+5)-spacetime with an embedded (1+3) brane is given. This solution localizes the zero modes of all kinds of matter fields and 4-gravity on the (1+3) brane by an increasing, transverse gravitational potential. This localization occurs despite the fact that the gravitational potential is not a decreasing exponential, and asymptotically approaches a finite value rather than zero.

hep-th↗

arXiv2003

Nonsingular Increasing Gravitational Potential for the Brane in 6D

We present a new (1+3)-brane solution to Einstein equations in (1+5)-space. As distinct from previous models this solution is free of singularities in the full 6-dimensional space-time. The gravitational potential transverse to the brane is an increasing (but not exponentially) function and asymptotically approaches a finite value. The solution localizes the zero modes of all kinds of matter fields and Newtonian gravity on the brane. An essential feature of the model is that different kind of matter fields have different localization radii.

hep-th↗

arXiv2002

Ginzburg - Landau equation from SU(2) gauge field theory

The dual superconductor picture of the QCD vacuum is thought to describe various aspects of the strong interaction including confinement. Ordinary superconductivity is described by the Ginzburg-Landau (GL) equation. In the present work we show that it is possible to arrive at a GL-like equation from pure SU(2) gauge theory. This is accomplished by using Abelian projection to split the SU(2) gauge fields into an Abelian subgroup and its coset. The two gauge field components of the coset part act as the effective, complex, scalar field of the GL equation. The Abelian part of the SU(2) gauge field is then analogous to the electromagnetic potential in the GL equation. An important aspect of the dual superconducting model is for the GL Lagrangian to have a spontaneous symmetry breaking potential, and the existence of Nielsen-Olesen flux tube solutions. Both of these require a tachyonic mass for the effective scalar field. Such a tachyonic mass term is obtained from the condensation of ghost fields.

hep-th↗

arXiv2001

Electrons as quasi-bosons in magnetic white dwarfs

A white dwarf star achieves its equilibrium from the balancing of the gravitational compression against the Fermi degeneracy pressure of the electron gas. In field theory there are examples (e.g. the monopole-charge system) where a strong magnetic field can transform a boson into a fermion or a fermion into a boson. In some condensed matter systems (e.g. fractional quantum Hall systems) a strong magnetic field can transform electrons into effective fermions, or effective anyons. Based on these examples we investigate the possibility that the strong magnetic fields of some white dwarfs may transform some fraction of the electrons into effective bosons. This could have consequences for the structure of highly magnetized white dwarfs. It would alter the mass-radius relationship, and in certain instances one could envision a scenario where a white dwarf below the Chandrasekhar limit could nevertheless collapse into a neutron star due to a weakening of the electron degeneracy pressure. In addition the transformation of electrons into effective bosons could result in the electrons Bose condensing, which could speed up the cooling rate of white dwarfs.

astro-ph↗

arXiv2000

Electromagnetic field angular momentum in condensed matter systems

Various electromagnetic systems can carry an angular momentum in their {\bf E} and {\bf B} fields. The electromagnetic field angular momentum (EMAM) of these systems can combine with the spin angular momentum to give composite fermions or composite bosons. In this paper we examine the possiblity that an EMAM could provide an explanation of the fractional quantum Hall effect (FQHE) which is complimentary to the Chern-Simons explanation. We also examine a toy model of a non-BCS superconductor (e.g. high $T_c$ superconductors) in terms of an EMAM. The models presented give a common, simple picture of these two systems in terms of an EMAM. The presence of an EMAM in these systems might be tested through the observation of the decay modes of a charged, spin zero unstable particle inside one of these systems.

cond-mat.mes-hall↗

arXiv1999

General relativistic analog solutions for Yang-Mills theory

Finding solutions to non-linear field theories, such as Yang-Mills theories or general relativity, is usually difficult. The field equations of Yang-Mills theories and general relativity are known to share some mathematical similarities, and this connection can be used to find solutions to one theory using known solutions of the other theory. For example, the Schwarzschild solutions of general relativity can be shown to have a mathematically similar counterpart in Yang-Mills theory. In this article we will discuss several solutions to the Yang-Mills equations which can be found using this connection between general relativity and Yang-Mills theory. Some comments about the possible physical meaning of these solutions will be discussed. In particular it will be argued that some of these analog solutions of Yang-Mills theory may have some connection with the confinement phenomenon. To this end we will briefly look at the motion of test particles moving in the background potential of the Schwarzschild analog solution.

hep-th↗

arXiv1999

Wormholes and Flux Tubes in Kaluza-Klein Theory

In this work spherically symmetric solutions to 5D Kaluza-Klein theory, with "electric" and/or "magnetic" fields are examined. Different relative strengths of the "electric" and "magnetic" charges of the solutions are studied by varying certain parameters in our metric ansatz. As the strengths of these two charges are varied the resultant spacetime exhibits an interesting "evolution".

gr-qc↗

arXiv1998

``Electromagnetic'' Contributrion to the Nucleon Spin

A possible resolution to the question of where the nucleon gets some portion of its internal angular momentum, not carried by the valence quarks, is given in terms of the electromagnetic field angular momentum of the nucleon. This field angular momentum is similiar in origin to that of the Thomson dipole (an electric charge and a magnetic monopole), but arises from the interaction of the quark electric charges and magnetic dipoles. Rough, order of magnitude calculations show that such a field angular momentum could provide some of the nucleon's spin. Under certain assumptions QCD should also exhibit a similiar field angular momentum coming from the interaction of color charges with color magnetic dipoles.

hep-ph↗

arXiv1997

Can Magnetic Charge and Quantum Mechanics Co-exist ?

It is proven that if more than a single magnetic charge exists it is impossible to define a proper quantum mechanical angular momentum operator for an electrically charged particle in the field of the magnetic charges. Assuming that quantum mechanics is correct we conclude that free magnetic charges (i.e. magnetic charges with a Coulomb-like magnetic field) can not exist. The only apparent way to avoid this conclusion is if magnetic charges do exist, they must be permanently confined in monopole anti-monopole pairs, much in the same way quarks are thought to be confined.

hep-th↗

arXiv1997

Restrictions on Magnetic Charge from Quantized Angular Momentum

Using the result that an electric charge - magnetic charge system carries an internal field angular momentum of $e g / 4 π$ we arrive at two restrictions on magnetic monopoles via the requirement of angular momentum quantization and/or conservation. First we show that magnetic charge should scale in the opposite way from electric charge. Second we show that free, unconfined monopoles seem to be inconsistent when one considers a magnetic charge in the vicinity of more than one electric charge.

hep-th↗

arXiv1997

Topological Electric Charge

By treating magnetic charge as a gauge symmetry through the introduction of a ``magnetic'' pseudo four-vector potential, it is shown that it is possible, using the 't Hooft-Polyakov construction, to obtain a topological electric charge. The mass of this electrically charged particle is found to be on the order of {1 / 137} M_W as opposed to the much larger mass (on the order of 137 M_W) of the magnetic soliton. Some model building possibilities are discussed.

hep-th↗

arXiv1997

Magnetic Charge as a ``Hidden'' Gauge Symmetry

A theory containing both electric and magnetic charges is formulated using two vector potentials, $A_μ$ and $C_μ$. This has the aesthetic advantage of treating electric and magnetic charges both as gauge charges, but it has the experimental disadvantage of introducing a second massless gauge boson (the ``magnetic'' photon) which is not observed. This problem is dealt with by using the Higgs mechanism to give a mass to one of the gauge bosons while the other remains massless. This effectively ``hides'' the magnetic charge, and the symmetry associated with it, when one is at an energy scale far enough removed from the scale of the symmetry breaking.

hep-th↗

arXiv1996

Yang-Mills Inspired Solutions for General Relativity

Several exact, cylindrically symmetric solutions to Einstein's vacuum equations are given. These solutions were found using the connection between Yang-Mills theory and general relativity. Taking known solutions of the Yang-Mills equations (e.g. the topological BPS monopole solutions) it is possible to construct exact solutions to the general relativistic field equations. Although the general relativistic solutions were found starting from known solutions of Yang-Mills theory they have different physical characteristics.

gr-qc↗