N=1 Super QCD and Fractional Branes

We show how to get the one-loop beta function and the chiral anomaly of N=1 Super QCD from a stack of fractional N D3-branes localized inside the world-volume of 2M fractional D7-branes on the orbifold C^3/(Z_2 x Z_2). They are obtained by analyzing the classical supergravity background generated by such a brane configuration, in the spirit of the gauge/gravity correspondence.Comment: 4 pages, LaTeX. Talk given at the IXth International Symposium on Particles, Strings and Cosmology PASCOS '03, Mumbai-India, January 3-8 2003. To appear in a special issue of Praman

Consistent Off-Shell Tree String Amplitudes

We give a construction of off-shell tree bosonic string amplitudes, based on the operatorial formalism of the $N$-string Vertex, with three external massless states both for open and closed strings by requiring their being projective invariant. In particular our prescription leads, in the low-energy limit, to the three-gluon amplitude in the usual covariant gauge.Comment: 12 pages. Introductory and final parts modified in order to make them more clear. Cosmetic changes in formulae (13) and (14). Some misprints correcte

N=2 four-dimensional gauge theories from fractional branes

This is a pedagogical and extended version of the results published in Refs. [1,2] and presented by the authors in various talks during the last year. We discuss the type II D-branes (both regular and fractional) of the orbifold R^{1,5}*R^4/Z_2, we determine their corresponding supergravity solution and show how this can be used to study the properties of N=2 super Yang-Mills. Supergravity is able to reproduce the perturbative moduli space of the gauge theory, while it does not encode the non-perturbative corrections. The short distance region of space-time, which corresponds to the infrared region of the gauge theory, is excised by an enhancon mechanism, and more states should be included in the low energy effective action in order to enter inside the enhancon and recover the instanton corrections. (To be published on a Memorial Volume commemorating Michael Marinov)Comment: 44 pages, AMS-LaTeX, no figure

Prescriptions for Off-Shell Bosonic String Amplitudes

We give, in the framework of the bosonic string theory, simple prescriptions for computing, at tree and one-loop levels, off-shell string amplitudes for open and closed string massless states. In particular we obtain a tree amplitude for three open strings that in the field theory limit coincides with the three-gluon vertex in the usual covariant gauge and two-string one-loop amplitudes satisfying the property of transversality.Comment: 11 pages, LaTeX, to appear in the proceedings of the workshop "Quantum Aspects of Gauge Theories, Supersymmetry and Unification", Corfu (Greece), 20-26 September 1998. Eq. (12) and numerical factors in eqs. (13) and (16) corrected; some minor changes and references adde

Non-perturbative effective model for the Higgs sector of the Standard Model

A non-perturbative effective model is derived for the Higgs sector of the standard model, described by a simple scalar theory. The renormalized couplings are determined by the derivatives of the Gaussian Effective Potential that are known to be the sum of infinite bubble graphs contributing to the vertex functions. A good agreement has been found with strong coupling lattice simulations when a comparison can be made

Fractional Branes and N=1 Gauge Theories

We discuss fractional D3-branes on the orbifold C^3/Z_2*Z_2. We study the open and the closed string spectrum on this orbifold. The corresponding N=1 theory on the brane has, generically, a U(N_1)*U(N_2)*U(N_3)*U(N_4) gauge group with matter in the bifundamental. In particular, when only one type of brane is present, one obtains pure N=1 Yang-Mills. We study the coupling of the branes to the bulk fields and present the corresponding supergravity solution, valid at large distances. By using a probe analysis, we are able to obtain the Wilsonian beta-function for those gauge theories that possess some chiral multiplet. Although, due to the lack of moduli, the probe technique is not directly applicable to the case of pure N=1 Yang-Mills, we point out that the same formula gives the correct result also for this case.Comment: 21 pages, AMS-LaTeX, v2: references added and typos correcte

Gauge theory renormalizations from the open bosonic string

We present a unified point of view on the different methods available in the literature to extract gauge theory renormalization constants from the low-energy limit of string theory. The Bern-Kosower method, based on an off-shell continuation of string theory amplitudes, and the construction of low-energy string theory effective actions for gauge particles, can both be understood in terms of strings interacting with background gauge fields, and thus reproduce, in the low-energy limit, the field theory results of the background field method. We present in particular a consistent off-shell continuation of the one-loop gluon amplitudes in the open bosonic string that reproduces exactly the results of the background field method in the Feynman gauge.Comment: 14 pages, latex, no figure

Printable Thin-Film Sol-Gel Lead Zirconate Titanate (PZT) Deposition Using NanoJet and Inkjet Printing Methods

Lead zirconate titanate (PZT) sub-5µm thin-films deposited using NanoJet and inkjet printing techniques will be presented. PZT, a perovskite ferroelectric ceramic, possesses both electrical and mechanical properties making it well suited for sensor and actuator applications. Large-scale and additive manufacturing of PZT deposition is currently unobtainable. A novel PZT sol-gel, therefore, comprised of an alkoxide mixture, was adapted for printing. Polyethylene glycol (PEG, 200MW) was discovered to be a superior film forming aid to the PZT sol-gel composite. PEG was added to the PZT composite to prevent film cracking upon gelation and thermal sintering. A powder-based sample of the PZT sol-gel was characterized using Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS), and Raman Spectroscopy. The Raman spectra displayed wavelength peaks around 200cm-1, 400cm-1, and 800cm-1 which indicated the desired 52/48 PZT molar ratio composite. The PZT sol-gel was printed into a thin-film using NanoJet and inkjet printing onto a cleaned stainless-steel substrate. The thin-film was thermally sintered at 700oC, and quenched in liquid nitrogen, to produce a defect-free thick film. The sub-five micron thick PZT films exhibited ferroelectric properties. This work begins to show a forward pathway for the larger scale manufacturing of device applications, such as concussion sensors, pressure sensors, and aerospace products

Sperm ultrastructure of an oviparous and an ovoviviparous onychophoran species (Peripatopsidae) with some phylogenetic considerations

The spermatozoa of the Australian oviparous Ooperipatellus insignis and the South African ovoviviparous Opisthopatus cinctipes (both: Onychophora, Peripatopsidae) were studied and compared with the spermatozoal patterns already described in the taxon. The spermatozoa of both species conform with the general plan described for the Onychophora: they are filiform cells formed, in sequence, by an elongated, fully condensed nucleus capped by an acrosome and surrounded by several spiral ridges; by a mitochondrial midpiece characteristically interpolated between the nucleus and a characteristic flagellum. Major differences between the spermatozoa of both species concern their acrosome organization. The correlation between the acrosomal pattern and the size and structure of the ovarial eggs (oocytes) in onychophorans has been investigated. A parsimony analysis was performed on 21 spermatozoal characters of the species considered. Its results are congruent with those of the traditional systematics. A new set of autapomorphies characterising onychophoran sperm is suggested and some of the spermatological homologies proposed between Onychophora and Euclitellata spermatozoa are critically discussed. Our analysis suggests that spermatozoal characters are good phylogenetic markers among onychophorans, also at low taxonomic level. Zusammenfassung Die Ultrastruktur der Spermien zweier Onychophoren-Arten (Peripatopsidae) wird vergleichend untersucht. Erstmals wird ein oviparer Vertreter berucksichtigt; namlich Ooperipatellus insignis vom Locus typicus; Mt. Macedon, Victoria, Australien. Seine Spermatozoen werden mit denen der ovoviviparen sudafrikanischen Art Opisthopatus cinctipes verglichen. Die Ergebnisse dieser Untersuchung werden mit verfugbaren Literaturdaten abgeglichen und ein Grundmuster fur Onychophoren-Spermien entwickelt. Die Spermien der beiden hier untersuchten Arten stimmen in ihrer Morphologie und Ultrastruktur im Wesentlichen mit dem bereits fur Onychophoren bekannten Muster uberein. Es sind fadige Zellen, die recht einheitlich aufgebaut sind. Sie weisen einen langlichen, kompakten Kern mit Akrosom-Kappe auf und sind spiralig von Furchen umgeben. Der mitochondriale Mittelbereich der Spermien liegt zwischen dem Nukleus und einem fur Onychophoren typischen Flagellum. Unterschiede betreffen dagegen die Organisation des Onychophoren-Akrosoms. Die mogliche Korrelation zwischen Akrosom-Ausbildung und Grose und Struktur der Ovarialeier wird untersucht. Basierend auf 21 Spermatozoen-Charakteren wird eine Parsimonie-Analyse durchgefuhrt. Die so gewonnenen Daten decken sich mit denjenigen der traditionellen Systematik. Die Spermien der Onychophoren weisen Merkmale auf, welche Autapomorphien des Taxon Onychophora sein konnen. Daruber hinaus werden mutmasliche Spermien-Homologien, die von verschiedenen Autoren fur die Taxa Onychophora und Euclitellata vorgeschlagen wurden, kritisch bewertet. Unsere Analyse zeigt, dass Spermien-Merkmale fur Onychophoren gute phylogenetische Marker darstellen, sogar auf Art-Niveau