Stationary Closed Strings in Five-dimensional Flat Spacetime

We investigate stationary rotating closed Nambu-Goto strings in five-dimensional flat spacetime. The stationary string is defined as a worldsheet that is tangent to a timelike Killing vector. Nambu-Goto equation of motion for the stationary string is reduces to the geodesic equation on the orbit space of the isometry group action generated by the Killing vector. We take a linear combination of a time-translation vector and space-rotation vectors as the Killing vector, and explicitly construct general solutions of stationary rotating closed strings in five-dimensional flat spacetime. We show a variety of their configurations and properties.Comment: 22 pages, 17 figure

Vector Positronium States in QED3

The homogeneous Bethe-Salpeter equation is solved in the quenched ladder approximation for the vector positronium states of 4-component quantum electrodynamics in 2 space and 1 time dimensions. Fermion propagator input is from a Rainbow approximation Dyson-Schwinger solution, with a broad range of fermion masses considered. This work is an extension of earlier work on the scalar spectrum of the same model. The non-relativistic limit is also considered via the large fermion mass limit. Classification of states via their transformation properties under discrete parity transformations allows analogies to be drawn with the meson spectrum of QCD.Comment: 24 pages, 2 encapsulated postscript figure

Stationary Rotating Strings as Relativistic Particle Mechanics

Stationary rotating strings can be viewed as geodesic motions in appropriate metrics on a two-dimensional space. We obtain all solutions describing stationary rotating strings in flat spacetime as an application. These rotating strings have infinite length with various wiggly shapes. Averaged value of the string energy, the angular momentum and the linear momentum along the string are discussed.Comment: 20pages, 7 figure

Gauge covariance and the fermion-photon vertex in three- and four- dimensional, massless quantum electrodynamics

In the quenched approximation, the gauge covariance properties of three vertex Ans\"{a}tze in the Schwinger-Dyson equation for the fermion self energy are analysed in three- and four- dimensional quantum electrodynamics. Based on the Cornwall-Jackiw-Tomboulis effective action, it is inferred that the spectral representation used for the vertex in the gauge technique cannot support dynamical chiral symmetry breaking. A criterion for establishing whether a given Ansatz can confer gauge covariance upon the Schwinger-Dyson equation is presented and the Curtis and Pennington Ansatz is shown to satisfy this constraint. We obtain an analytic solution of the Schwinger-Dyson equation for quenched, massless three-dimensional quantum electrodynamics for arbitrary values of the gauge parameter in the absence of dynamical chiral symmetry breaking.Comment: 17 pages, PHY-7143-TH-93, REVTE

The analytic structure of heavy quark propagators

The renormalised quark Dyson-Schwinger equation is studied in the limit of the renormalised current heavy quark mass m_R --> infinity. We are particularly interested in the analytic pole structure of the heavy quark propagator in the complex momentum plane. Approximations in which the quark-gluon vertex is modelled by either the bare vertex or the Ball-Chiu Ansatz, and the Landau gauge gluon propagator takes either a gaussian form or a gaussian form with an ultraviolet asymptotic tail are used.Comment: 21 pages Latex and 5 postscript figures. The original version of this paper has been considerably extended to include a formalism dealing with the renormalised heavy quark Dyson-Schwinger equation and uses a more realistic Ansatz for the gluon propagator

Understanding the physics of oligonucleotide microarrays: the Affymetrix spike-in data reanalysed

The Affymetrix U95 and U133 Latin Square spike-in datasets are reanalysed, together with a dataset from a version of the U95 spike-in experiment without a complex non-specific background. The approach uses a physico-chemical model which includes the effects the specific and non-specific hybridisation and probe folding at the microarray surface, target folding and hybridisation in the bulk RNA target solution, and duplex dissociation during the post-hybridisatoin washing phase. The model predicts a three parameter hyperbolic response function that fits well with fluorescence intensity data from all three datasets. The importance of the various hybridisation and washing effects in determining each of the three parameters is examined, and some guidance is given as to how a practical algorithm for determining specific target concentrations might be developed.Comment: 32 pages, 13 figures, minor amendment

Two Archeological Surveys In The Texas Department Of Transportations Atlanta District: FM 450 At Little Cypress Bayou, Harrison County (CSJ 0843-02-012), And County Road 4114 At Brutons Creek, Morris County (CSJ 0919-20-030)

Prewitt and Associates, Inc., was contracted by the Texas Department of Transportation (TxDOT) to perform two intensive archeological surveys in TxDOT’s Atlanta District under Texas Antiquities Permit No. 6385. This work was completed prior to replacement of a bridge and realignment of approaches on Farm-to-Market Road (FM) 450 at Little Cypress Bayou in Harrison County (CSJ 0843-02-012) and replacement of a bridge and improvement of approaches on County Road 4114 at Brutons Creek in Morris County (CSJ 0919-20-030). The Area of Potential Effects (APE) for the FM 450 project is 50 acres and includes existing and new TxDOT right of way; approximately half of the APE was surveyed in 2010 (McKee 2010). The APE for the County Road 4114 project is 1.2 acres and includes a short segment of existing right of way and 0.9 acres of temporary construction easements. Prewitt and Associates archeologists surveyed the remaining 25 acres of the FM 450 APE and the County Road 4114 APE in December 2012 and January 2013. These investigations required a total of about 11 person-days of effort. The FM 450 survey included the excavation of 50 shovel tests and 11 trenches. This effort identified a small amount of modern trash on the upland margin at the north end of the project area and prehistoric site 41HS973 on the floodplain near Little Cypress Bayou. Site 41HS973 consists of a diffuse scatter of seven pieces of lithic debitage identified on two sandy rises on the Little Cypress Bayou floodplain. The investigation indicated that the archeological deposits in the investigated part of the site lack both integrity and significance. Thus, Prewitt and Associates recommends that the recorded portion of 41HS973 is not eligible for listing in the National Register of Historic Places under Criterion D (36 CFR 60.4; 36 CFR 800.4, 5) or designation as a State Archeological Landmark (13 TAC 26.2, 8). The County Road 4114 survey included the excavation of 15 shovel tests and 4 trenches in and adjacent to the temporary construction easements. No archeological materials or deposits were identified during this investigation. Both surveys were conducted under no artifact collection policies. Identified artifacts were noted, briefly described, and returned to the point of recovery

Nonperturbative Vertices in Supersymmetric Quantum Electrodynamics

We derive the complete set of supersymmetric Ward identities involving only two- and three- point proper vertices in supersymmetric QED. We also present the most general form of the proper vertices consistent with both the supersymmetric and U(1) gauge Ward identities. These vertices are the supersymmetric equivalent of the non supersymmetric Ball-Chiu vertices.Comment: seventeen pages late