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in subjects: "Space-Time"

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Two exercises in supersymmetry: a low-energy supergravity model and free string field theory

The new features of a supersymmetric standard model in the presence of heavy families are studied. The minimal set of Higgs fields, the desert between the electroweak and the grand unification scale and perturbative values of the dimensionless parameters throughout this region are assumed. Using the numerical as well as the approximate analytic solution of the renormalization group equations, the evolution of all the parameters of the theory are studied in the case of large Yukawa couplings for… more

Date: September 1, 1986

Creator: Preitschopf, C.R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Diffraction scattering and the parton model in QCD

Arguments are presented that the validity of the parton model for hadron scattering in QCD is directly related to the occurrence of the Critical Pomeron description of diffraction scattering. An attractive route suggested for Electroweak and Grand Unification is also briefly described.

Date: January 1, 1985

Creator: White, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A superstring theory underview

I give a brief survey of the current status of superstring phenomenology, with an emphasis on the (currently unrealized) possibility of obtaining model-independent results. 40 refs., 9 figs.

Date: November 1, 1989

Creator: Dixon, L. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Strings in four dimensions

We review the construction and properties of four dimensional string models, using free fermions on the world-sheet. We prove that as opposed to gauge symmetries, broken space-time supersymmetry can only be restored continuously by decompactification. 40 refs.

Date: January 1, 1988

Creator: Bachas, C. P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Exploitation of parallelism in climate models

The US Department of Energy (DOE) through its CHAMMP initiative, hopes to develop the capability to make meaningful regional climate forecasts on time scales exceeding a decade, such capability to be based on numerical prediction type models. We propose research to contribute to each of the specific items enumerated in the CHAMMP announcement (Notice 9103); i.e., to consider theoretical limits to prediction of climate and climate change on appropriate time scales, to develop new mathematical te… more

Date: January 1, 1992

Creator: Baer, F.; Tribbia, J.J. & Williamson, D.L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Hamiltonian flows, Su( infinity ), SO( infinity ), USp( infinity ), and strings

Based on the infinite-dimensional algebras we have introduced, SU({infinity}) is identified with general Hamiltonian flows in 2-d phase-space, SO({infinity}) with flows generated by x-p-odd Hamiltonians, and USp({infinity}) with those of Hamiltonians of special symmetry. Gauge theories for SU({infinity}), SO({infinity}), and USp({infinity}) are thus formulated in terms of surface (sheet) coordinates for toroidal phase-space. Spacetime-independent configurations of their gauge fields directly yi… more

Date: January 1, 1989

Creator: Zachos, C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Invariance, symmetry and periodicity in gauge theories

The interplay between gauge transformations and coordinate transformations is discussed; the theory will aid in understanding the mixing of space-time and internal degrees of freedom. The subject is presented under the following headings: coordinate transformation laws for arbitrary fields, coordinate transformation laws for gauge fields, properties of symmetric gauge fields, construction of symmetric gauge fields, physical significance of gauge transformations, and magnetic monopole topology w… more

Date: February 1, 1980

Creator: Jackiw, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Effective theories and thresholds in particle physics

The role of effective theories in probing a more fundamental underlying theory and in indicating new physics thresholds is discussed, with examples from the standard model and more speculative applications to superstring theory. 38 refs.

Date: June 7, 1991

Creator: Gaillard, M. K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Chiral anomalies and differential geometry

Some properties of chiral anomalies are described from a geometric point of view. Topics include chiral anomalies and differential forms, transformation properties of the anomalies, identification and use of the anomalies, and normalization of the anomalies. 22 references. (WHK)

Date: October 1, 1983

Creator: Zumino, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Light-Front Holography and Hadronization at the Amplitude Level

The correspondence between theories in anti-de Sitter space and conformal field theories in physical space-time leads to an analytic, semiclassical model for strongly-coupled QCD which has scale invariance at short distances and color confinement at large distances. Light-front holography is a remarkable feature of AdS/CFT: it allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a rela… more

Date: July 25, 2008

Creator: Brodsky, Stanley J.; de Teramond, Guy & Shrock, Robert

Item Type: Article

Partner: UNT Libraries Government Documents Department

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World Sheet Commuting beta-gamma CFT and Non-Relativistic StringTheories

We construct a sigma model in two dimensions with Galilean symmetry in flat target space similar to the sigma model of the critical string theory with Lorentz symmetry in 10 flat spacetime dimensions. This is motivated by the works of Gomis and Ooguri[1] and Danielsson et. al.[2, 3]. Our theory is much simpler than their theory and does not assume a compact coordinate. This non-relativistic string theory has a bosonic matter {beta}{gamma} CFT with the conformal weight of {beta} as 1. It is natu… more

Date: August 30, 2007

Creator: Kim, Bom Soo

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Mixed Alcohol Synthesis Catalyst Screening

National Renewable Energy Laboratory (NREL) and Pacific Northwest National Laboratory (PNNL) are conducting research to investigate the feasibility of producing mixed alcohols from biomass-derived synthesis gas (syngas). PNNL is tasked with obtaining commercially available or preparing promising mixed-alcohol catalysts and screening them in a laboratory-scale reactor system. Commercially available catalysts and the most promising experimental catalysts are provided to NREL for testing using a s… more

Date: September 3, 2007

Creator: Gerber, Mark A.; White, James F. & Stevens, Don J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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M-theory through the looking glass: Tachyon condensation in the E8 heterotic string

We study the spacetime decay to nothing in string theory and M-theory. First we recall a nonsupersymmetric version of heterotic M-theory, in which bubbles of nothing -- connecting the two E_8 boundaries by a throat -- are expected to be nucleated. We argue that the fate of this system should be addressed at weak string coupling, where the nonperturbative instanton instability is expected to turn into a perturbative tachyonic one. We identify the unique string theory that could describe this pro… more

Date: September 20, 2007

Creator: Horava, Petr; Horava, Petr & Keeler, Cynthia A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Light-Front Holography and Novel Effects in QCD

The correspondence between theories in anti-de Sitter space and conformal field theories in physical space-time leads to an analytic, semiclassical model for strongly-coupled QCD. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons at the amplitude level. We identify the AdS coordinate z with an invariant light-front coordin… more

Date: December 18, 2008

Creator: Brodsky, Stanley J. & de Teramond, Guy F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Strings on AdS2 and the high-energy limit of noncritical M-theory

Abstract. Noncritical M-theory in 2+1 dimensions has been defined as a double-scaling limit of a nonrelativistic Fermi liquid on a flat two-dimensional plane. Here we study this noncritical M-theory in the limit of high energies, analogous to the alpha' --> infinity limit of string theory. In the related case of two-dimensional Type 0A strings, it has been argued that the conformal alpha' --> infinity limit leads to AdS_2 with a propagating fermion whose mass is set by the value o… more

Date: April 16, 2007

Creator: Horava, Petr; Horava, Petr & Keeler, Cynthia A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Precision cosmology and the landscape

After reviewing the cosmological constant problem -- why is Lambda not huge? -- I outline the two basic approaches that had emerged by the late 1980s, and note that each made a clear prediction. Precision cosmological experiments now indicate that the cosmological constant is nonzero. This result strongly favors the environmental approach, in which vacuum energy can vary discretely among widely separated regions in the universe. The need to explain this variation from first principles constitut… more

Date: October 1, 2006

Creator: Bousso, Raphael & Bousso, Raphael

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

AdS/CFT and Light-Front QCD

The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. The AdS/CFT correspondence also provides insights into the inherently nonperturbative aspects of QCD such as the orbital and radial spectra of hadrons and the form of hadronic wavefunctions. In particular… more

Date: February 4, 2008

Creator: Brodsky, Stanley J. & de Teramond, Guy F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Geometric Gyrokinetic Theory for Edge Plasma

It turns out that gyrokinetic theory can be geometrically formulated as special cases of a geometrically generalized Vlasov-Maxwell system. It is proposed that the phase space of the spacetime is a 7-dimensional fiber bundle P over the 4-dimensional spacetime M, and that a Poincare-Cartan-Einstein 1-form {gamma} on the 7-dimensional phase space determines particles worldlines in the phase space. Through Liouville 6-form {Omega} and fiber integral, the 1-form {gamma} also uniquely defines a geom… more

Date: January 18, 2007

Creator: Qin, H; Cohen, R H; Nevins, W M & Xu, X Q

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Automated analysis for detecting beams in laser wakefield simulations

Laser wakefield particle accelerators have shown the potential to generate electric fields thousands of times higher than those of conventional accelerators. The resulting extremely short particle acceleration distance could yield a potential new compact source of energetic electrons and radiation, with wide applications from medicine to physics. Physicists investigate laser-plasma internal dynamics by running particle-in-cell simulations; however, this generates a large dataset that requires t… more

Date: July 3, 2008

Creator: Ushizima, Daniela M.; Rubel, Oliver; Prabhat, Mr.; Weber, Gunther H.; Bethel, E. Wes; Aragon, Cecilia R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A variational solution to the transport equation subject to an affine constraint.

We establish an existence and uniqueness theorem for the transport equation subject to an inequality affine constraint, viewed as a constrained optimization problem. Then we derive a Space-Time Integrated Least Squares (STILS) scheme for its numerical approximation. Furthermore, we discuss some L{sup 2}-projection strategies and with numerical examples we show that there are not relevant for that problem.

Date: February 1, 2004

Creator: Pousin, Jerome G. (National Institute of Applied Sciences, Villeurbanne Cedex, France); Najm, Habib N.; Picq, Martine (National Institute of Applied Sciences, Villeurbanne Cedex, France) & Pebay, Philippe Pierre

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Evaluation of Promoters for Rhodium-Based Catalysts for Mixed Alcohol Synthesis

Pacific Northwest National Laboratory (PNNL) and National Renewable Energy Laboratory (NREL) are conducting research to investigate the feasibility of producing mixed alcohols from biomass-derived synthesis gas (syngas). PNNL is tasked with obtaining commercially-available catalysts or preparing promising mixed-alcohol catalysts and screening them in a laboratory-scale reactor system. Commercially-available catalysts and the most promising experimental catalysts are provided to NREL for testing… more

Date: December 8, 2008

Creator: Gerber, Mark A.; White, James F.; Gray, Michel J. & Stevens, Don J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Scaling Behavior of the First Arrival Time of a Random-Walking Magnetic Domain

We report a universal scaling behavior of the first arrival time of a traveling magnetic domain wall into a finite space-time observation window of a magneto-optical microscope enabling direct visualization of a Barkhausen avalanche in real time. The first arrival time of the traveling magnetic domain wall exhibits a nontrivial fluctuation and its statistical distribution is described by universal power-law scaling with scaling exponents of 1.34 {+-} 0.07 for CoCr and CoCrPt films, despite thei… more

Date: February 4, 2008

Creator: Im, M. Y.; Lee, S. H.; Kim, D. H.; Fischer, P. & Shin, S. C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Final Technical Report on Scaling Models of the Internal Variability of Clouds DoE Grant No. DE-FG02-04ER63773

The purpose of this proposal is to gain a better understanding of the space-time correlations of atmospheric fluctuations in clouds through application of methods from statistical physics to high resolution, continuous data sets of cloud observations available at the Department of Energy Atmospheric Radiation Measurement Program archive. In this report we present the accomplishments achieved during the four year period. Starting with the most recent one, we report on two break-throughs in our r… more

Date: April 24, 2008

Creator: Ivanova, Kristinka

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Quantum geometry and gravitational entropy

Most quantum states have wavefunctions that are widely spread over the accessible Hilbert space and hence do not have a good description in terms of a single classical geometry. In order to understand when geometric descriptions are possible, we exploit the AdS/CFT correspondence in the half-BPS sector of asymptotically AdS_5 x S5 universes. In this sector we devise a"coarse-grained metric operator" whose eigenstates are well described by a single spacetime topology and geometry. We s… more

Date: May 29, 2007

Creator: Simon, Joan; Balasubramanian, Vijay; Czech, Bart Iomiej; Larjo, Klaus; Marolf, Donald & Simon, Joan

Item Type: Article

Partner: UNT Libraries Government Documents Department