Non-perturbative String Theory from Water Waves (open access)

Non-perturbative String Theory from Water Waves

We use a combination of a 't Hooft limit and numerical methods to find non-perturbative solutions of exactly solvable string theories, showing that perturbative solutions in different asymptotic regimes are connected by smooth interpolating functions. Our earlier perturbative work showed that a large class of minimal string theories arise as special limits of a Painleve IV hierarchy of string equations that can be derived by a similarity reduction of the dispersive water wave hierarchy of differential equations. The hierarchy of string equations contains new perturbative solutions, some of which were conjectured to be the type IIA and IIB string theories coupled to (4, 4k ? 2) superconformal minimal models of type (A, D). Our present paper shows that these new theories have smooth non-perturbative extensions. We also find evidence for putative new string theories that were not apparent in the perturbative analysis.
Date: June 14, 2012
Creator: Iyer, Ramakrishnan; Johnson, Clifford V. & Pennington, Jeffrey S.
Object Type: Article
System: The UNT Digital Library
A Reconnection Switch to Trigger gamma-Ray Burst Jet Dissipation (open access)

A Reconnection Switch to Trigger gamma-Ray Burst Jet Dissipation

Prompt gamma-ray burst (GRB) emission requires some mechanism to dissipate an ultrarelativistic jet. Internal shocks or some form of electromagnetic dissipation are candidate mechanisms. Any mechanism needs to answer basic questions, such as what is the origin of variability, what radius does dissipation occur at, and how does efficient prompt emission occur. These mechanisms also need to be consistent with how ultrarelativistic jets form and stay baryon pure despite turbulence and electromagnetic reconnection near the compact object and despite stellar entrainment within the collapsar model. We use the latest magnetohydrodynamical models of ultrarelativistic jets to explore some of these questions in the context of electromagnetic dissipation due to the slow collisional and fast collisionless reconnection mechanisms, as often associated with Sweet-Parker and Petschek reconnection, respectively. For a highly magnetized ultrarelativistic jet and typical collapsar parameters, we find that significant electromagnetic dissipation may be avoided until it proceeds catastrophically near the jet photosphere at large radii (r {approx} 10{sup 13}-10{sup 14}cm), by which the jet obtains a high Lorentz factor ({gamma} {approx} 100-1000), has a luminosity of L{sub j} {approx} 10{sup 50}-10{sup 51} erg s{sup -1}, has observer variability timescales of order 1s (ranging from 0.001-10s), achieves {gamma}{theta}{sub j} {approx} 10-20 …
Date: March 14, 2012
Creator: McKinney, Jonathan C. & Uzdensky, Dmitri A.
Object Type: Article
System: The UNT Digital Library
On the Toroidal Plasma Rotations Induced by Lower Hybrid Waves (open access)

On the Toroidal Plasma Rotations Induced by Lower Hybrid Waves

A theoretical model is developed to explain the plasma rotations induced by lower hybrid waves in Alcator C-Mod. In this model, torodial rotations are driven by the Lorentz force on the bulk electron flow across flux surfaces, which is a response of the plasma to the resonant-electron flow across flux surfaces induced by the lower hybrid waves. The flow across flux surfaces of the resonant electrons and the bulk electrons are coupled through the radial electric fi eld initiated by the resonant electrons, and the friction between ions and electrons transfers the toroidal momentum to ions from electrons. An improved quasilinear theory with gyrophase dependent distribution function is developed to calculate the perpendicular resonant-electron flow. Toroidal rotations are determined using a set of fluid equations for bulk electrons and ions, which are solved numerically by a fi nite- difference method. Numerical results agree well with the experimental observations in terms of flow pro file and amplitude. The model explains the strong correlation between torodial flow and internal inductance observed experimentally, and predicts both counter-current and co-current flows, depending on the perpendicular wave vectors of the lower hybrid waves. __________________________________________________
Date: November 14, 2012
Creator: Xiaoyin Guan, Hong Qin, Jian Liu and Nathaniel J. Fisch
Object Type: Report
System: The UNT Digital Library
$A^t_{FB}$ Meets LHC (open access)

$A^t_{FB}$ Meets LHC

The recent Tevatron measurement of the forward-backward asymmetry of the top quark shows an intriguing discrepancy with Standard Model expectations, particularly at large t{bar t} invariant masses. Measurements of this quantity are subtle at the LHC, due to its pp initial state, however, one can define a forward-central-charge asymmetry which captures the physics. We study the capability of the LHC to measure this asymmetry and find that within the SM a measurement at the 5{sigma} level is possible with roughly 60 fb{sup -1} at {radical}s = 14 TeV. If nature realizes a model which enhances the asymmetry (as is necessary to explain the Tevatron measurements), a significant difference from zero can be observed much earlier, perhaps even during early LHC running at {radical}s = 7 TeV. We further explore the capabilities of the 7 TeV LHC to discover resonances or contact interactions which modify the t{bar t} invariant mass distribution using recent boosted top tagging techniques. We find that TeV-scale color octet resonances can be discovered, even with small coupling strengths and that contact interactions can be probed at scales exceeding 6 TeV. Overall, the LHC has good potential to clarify the situation with regards to the Tevatron forward-backward measurement.
Date: February 14, 2012
Creator: Hewett, JoAnne L.; /SLAC; Shelton, Jessie; U., /Yale; Spannowsky, Michael; U., /Oregon et al.
Object Type: Article
System: The UNT Digital Library
Higgs, Binos and Gluinos: Split Susy within Reach (open access)

Higgs, Binos and Gluinos: Split Susy within Reach

Recent results from the LHC for the Higgs boson with mass between 142 GeV {approx}< m{sub h{sup 0}} {approx}< 147 GeV points to PeV-scale Split Supersymmetry. This article explores the consequences of a Higgs mass in this range and possible discovery modes for Split Susy. Moderate lifetime gluinos, with decay lengths in the 25 {micro}m to 10 yr range, are its imminent smoking gun signature. The 7TeV LHC will be sensitive to the moderately lived gluinos and trilepton signatures from direct electroweakino production. Moreover, the dark matter abundance may be obtained from annihilation through an s-channel Higgs resonance, with the LSP almost purely bino and mass m{sub {chi}{sub 1}{sup 0}} {approx_equal} 70 GeV. The Higgs resonance region of Split Susy has visible signatures in dark matter direct and indirect detection and electric dipole moment experiments. If the anomalies go away, the majority of Split Susy parameter space will be excluded.
Date: September 14, 2012
Creator: Alves, Daniele S.M.; Izaguirre, Eder; /SLAC /Stanford U., Phys. Dept.; Wacker, Jay G. & /SLAC /Stanford U., ITP
Object Type: Article
System: The UNT Digital Library
Evaluation of Representative Smart Grid Investment Grant Project Technologies: Distributed Generation (open access)

Evaluation of Representative Smart Grid Investment Grant Project Technologies: Distributed Generation

This document is one of a series of reports estimating the benefits of deploying technologies similar to those implemented on the Smart Grid Investment Grant (SGIG) projects. Four technical reports cover the various types of technologies deployed in the SGIG projects, distribution automation, demand response, energy storage, and renewables integration. A fifth report in the series examines the benefits of deploying these technologies on a national level. This technical report examines the impacts of addition of renewable resources- solar and wind in the distribution system as deployed in the SGIG projects.
Date: February 14, 2012
Creator: Singh, Ruchi & Vyakaranam, Bharat GNVSR
Object Type: Report
System: The UNT Digital Library
Magneto-optical Signatures of a Cascade of Transitions in La 1.875Ba 0.125CuO 4 (open access)

Magneto-optical Signatures of a Cascade of Transitions in La 1.875Ba 0.125CuO 4

Recent experiments on the original cuprate high temperature superconductor, La{sub 2-x}Ba{sub x}CuO{sub 4}, revealed a remarkable sequence of phase transitions. Here we investigate such crystals with polar Kerr effect which is sensitive to time-reversal-symmetry breaking. Concurrent birefringence measurements accurately locate the structural phase transitions from high-temperature tetragonal to low temperature orthorhombic, and then to lower temperature tetragonal, at which temperature a strong Kerr signal onsets. Hysteretic behavior of the Kerr signal suggests that time-reversal symmetry is already broken well above room temperature, an effect that was previously observed in high quality YBa{sub 2}Cu{sub 3}O{sub 6+x} crystals.
Date: September 14, 2012
Creator: Karapetyan, Hovnatan; Hucker, M.; Gu, G. D.; Tranquada, J. M.; Fejer, M. M.; Xia, Jing et al.
Object Type: Article
System: The UNT Digital Library
Induction Consolidation of Thermoplastic Composites Using Smart Susceptors (open access)

Induction Consolidation of Thermoplastic Composites Using Smart Susceptors

This project has focused on the area of energy efficient consolidation and molding of fiber reinforced thermoplastic composite components as an energy efficient alternative to the conventional processing methods such as autoclave processing. The expanding application of composite materials in wind energy, automotive, and aerospace provides an attractive energy efficiency target for process development. The intent is to have this efficient processing along with the recyclable thermoplastic materials ready for large scale application before these high production volume levels are reached. Therefore, the process can be implemented in a timely manner to realize the maximum economic, energy, and environmental efficiencies. Under this project an increased understanding of the use of induction heating with smart susceptors applied to consolidation of thermoplastic has been achieved. This was done by the establishment of processing equipment and tooling and the subsequent demonstration of this fabrication technology by consolidating/molding of entry level components for each of the participating industrial segments, wind energy, aerospace, and automotive. This understanding adds to the nation's capability to affordably manufacture high quality lightweight high performance components from advanced recyclable composite materials in a lean and energy efficient manner. The use of induction heating with smart susceptors is a precisely controlled …
Date: June 14, 2012
Creator: Matsen, Marc R
Object Type: Report
System: The UNT Digital Library
Design Considerations for an MEBT Chopper Absorber of 2.1 MeV H- at the Project X Injector Experiment at Fermilab (open access)

Design Considerations for an MEBT Chopper Absorber of 2.1 MeV H- at the Project X Injector Experiment at Fermilab

The Project X Injector Experiment (PIXIE) will be a prototype of the Project X front end that will be used to validate the design concept and decrease technical risks. One of the most challenging components of PIXIE is the wide-band chopping system of the Medium Energy Beam Transport (MEBT) section, which will form an arbitrary bunch pattern from the initially CW 162.5 MHz 5mA beam. The present scenario assumes diverting 80% of the beam to an absorber to provide a beam with the average current of 1mA to SRF linac. This absorber must withstand a high level of energy deposition and high ion fluence, while being positioned in proximity of the superconductive cavities. This paper discusses design considerations for the absorber. Thermal and mechanical analyses of a conceptual design are presented, and future plans for the fabrication and testing of a prototype are described.
Date: May 14, 2012
Creator: Baffes, C.; Awida, M.; Chen, A.; Eidelman, Y.; Lebedev, V.; Prost, L. et al.
Object Type: Article
System: The UNT Digital Library
TESTING AND CHARACTERIZATION OF ENGINEERED FORMS OF MONOSODIUM TITANATE (MST) (open access)

TESTING AND CHARACTERIZATION OF ENGINEERED FORMS OF MONOSODIUM TITANATE (MST)

Engineered forms of MST and mMST were prepared at ORNL using an internal gelation process. Samples of these two materials were characterized at SRNL to examine particle size and morphology, peroxide content, tapped densities, and Na, Ti, and C content. Batch contact tests were also performed to examine the performance of the materials. The {sup E}mMST material was found to contain less than 10% of the peroxide found in a freshly prepared batch of mMST. This was also evidenced in batch contact testing with both simulated and actual waste, where little difference in performance was seen between the two engineered materials, {sup E}MST and {sup E}mMST. Based on these results, attempts were made to increase the peroxide content of the materials by post-treatment with hydrogen peroxide. The peroxide treatment resulted in a slight ({approx}10%) increase in peroxide content; however, the peroxide:Ti molar ratio was still much lower ({approx}0.1 X) than what is seen in a freshly prepared batch of mMST. Testing with simulated waste showed the performance of the peroxide treated materials was improved. Batch contact tests were also performed with an earlier (2003) prepared lot of {sup E}MST to examine the effect of ionic strength on the performance of …
Date: May 14, 2012
Creator: Taylor-Pashow, K.; Nash, C. & Hobbs, D.
Object Type: Report
System: The UNT Digital Library
W+n-jet Predictions at NLO Matched with a Parton Shower (open access)

W+n-jet Predictions at NLO Matched with a Parton Shower

None
Date: December 14, 2012
Creator: Siegert, Frank; Hoeche, Stefan; Krauss, Frank & Schonherr, Marek
Object Type: Article
System: The UNT Digital Library
STATISTICAL ANALYSIS OF TANK 5 FLOOR SAMPLE RESULTS (open access)

STATISTICAL ANALYSIS OF TANK 5 FLOOR SAMPLE RESULTS

Sampling has been completed for the characterization of the residual material on the floor of Tank 5 in the F-Area Tank Farm at the Savannah River Site (SRS), near Aiken, SC. The sampling was performed by Savannah River Remediation (SRR) LLC using a stratified random sampling plan with volume-proportional compositing. The plan consisted of partitioning the residual material on the floor of Tank 5 into three non-overlapping strata: two strata enclosed accumulations, and a third stratum consisted of a thin layer of material outside the regions of the two accumulations. Each of three composite samples was constructed from five primary sample locations of residual material on the floor of Tank 5. Three of the primary samples were obtained from the stratum containing the thin layer of material, and one primary sample was obtained from each of the two strata containing an accumulation. This report documents the statistical analyses of the analytical results for the composite samples. The objective of the analysis is to determine the mean concentrations and upper 95% confidence (UCL95) bounds for the mean concentrations for a set of analytes in the tank residuals. The statistical procedures employed in the analyses were consistent with the Environmental Protection Agency …
Date: March 14, 2012
Creator: Shine, E.
Object Type: Report
System: The UNT Digital Library
Monte Carlo Comparisons to a Cryogenic Dark Matter Search Detector with Low Transition-Edge-Sensor Transition Temperature (open access)

Monte Carlo Comparisons to a Cryogenic Dark Matter Search Detector with Low Transition-Edge-Sensor Transition Temperature

None
Date: September 14, 2012
Creator: Leman, S. W
Object Type: Article
System: The UNT Digital Library
Fundamental Physics at the Intensity Frontier (open access)

Fundamental Physics at the Intensity Frontier

None
Date: December 14, 2012
Creator: Hewett, J. L.; Weerts, H.; Brock, R.; Butler, J. N.; Casey, B. C. K.; Collar, J. et al.
Object Type: Article
System: The UNT Digital Library
Measurement of the Cosmic Ray e+ plus e- Spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope (open access)

Measurement of the Cosmic Ray e+ plus e- Spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope

Designed as a high-sensitivity gamma-ray observatory, the Fermi Large Area Telescope is also an electron detector with a large acceptance exceeding 2 m{sup 2}sr at 300 GeV. Building on the gamma-ray analysis, we have developed an efficient electron detection strategy which provides sufficient background rejection for measurement of the steeply-falling electron spectrum up to 1 TeV. Our high precision data show that the electron spectrum falls with energy as E{sup -3.0} and does not exhibit prominent spectral features. Interpretations in terms of a conventional diffusive model as well as a potential local extra component are briefly discussed.
Date: May 14, 2012
Creator: Abdo, Aous A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Ajello, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. et al.
Object Type: Article
System: The UNT Digital Library
Status report on improved understanding of creep-fatigue damage in advanced materials. (open access)

Status report on improved understanding of creep-fatigue damage in advanced materials.

None
Date: August 14, 2012
Creator: Li, M.; Majumdar, S.; Soppet, W. K.; Rink, D. & Natesan, K.
Object Type: Report
System: The UNT Digital Library
Analysing the Effect on CMB in a Parity and Charge Parity Violating Varying Alpha Theory (open access)

Analysing the Effect on CMB in a Parity and Charge Parity Violating Varying Alpha Theory

In this paper we study in detail the effect of our recently proposed model of parity and charge-parity (PCP) violating varying alpha on the Cosmic Microwave Background (CMB) photon passing through the intra galaxy-cluster medium (ICM). The ICM is well known to be composed of magnetized plasma. According to our model, the polarization and intensity of the CMB would be affected when traversing through the ICM due to non-trivial scalar photon interactions. We have calculated the evolution of such polarization and intensity collectively, known as the stokes parameters of the CMB photon during its journey through the ICM and tested our results against the Sunyaev-Zel'dovich (SZ) measurement on Coma galaxy cluster. Our model contains a PCP violating parameter, {beta}, and a scale of alpha variation {omega}. Using the derived constrained on the photon-to-scalar conversion probability, {bar P}{sub {gamma}{yields}{phi}}, for Coma cluster in ref.[34] we found a contour plot in the ({omega},{beta}) parameter plane. The {beta} = 0 line in this parameter space corresponds to well-studied Maxwell-dilaton type models which has lower bound on {omega} {approx}> 6.4 x 10{sup 9} GeV. In general, as the absolute value of {beta} increases, lower bound on {omega} also increases. Our model in general predicts …
Date: September 14, 2012
Creator: Maity, Debaprasad; /NCTS, Taipei /Taiwan, Natl. Taiwan U.; Chen, Pisin & /NCTS, Taipei /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC
Object Type: Article
System: The UNT Digital Library
Summary of Lepton Photon 2011 (open access)

Summary of Lepton Photon 2011

In this lecture, I summarize developments presented at the Lepton Photon 2011 conference and give my perspective on the current situation in high-energy physics. I am grateful to the organizers of Lepton Photon 2011 for providing us a very pleasant and simulating week in Mumbai. This year's Lepton Photon conference has covered the full range of subjects that fall within the scope of high-energy physics, including connections to cosmology, nuclear physics, and atomic physics. The experiments that were discussed detect particles ranging in energy from radio frequencies to EeV.
Date: March 14, 2012
Creator: Peskin, Michael E.
Object Type: Article
System: The UNT Digital Library
CDP - Adaptive Supervisory Control and Data Acquisition (SCADA) Technology for Infrastructure Protection (open access)

CDP - Adaptive Supervisory Control and Data Acquisition (SCADA) Technology for Infrastructure Protection

Supervisory Control and Data Acquisition (SCADA) Systems are a type of Industrial Control System characterized by the centralized (or hierarchical) monitoring and control of geographically dispersed assets. SCADA systems combine acquisition and network components to provide data gathering, transmission, and visualization for centralized monitoring and control. However these integrated capabilities, especially when built over legacy systems and protocols, generally result in vulnerabilities that can be exploited by attackers, with potentially disastrous consequences. Our research project proposal was to investigate new approaches for secure and survivable SCADA systems. In particular, we were interested in the resilience and adaptability of large-scale mission-critical monitoring and control infrastructures. Our research proposal was divided in two main tasks. The first task was centered on the design and investigation of algorithms for survivable SCADA systems and a prototype framework demonstration. The second task was centered on the characterization and demonstration of the proposed approach in illustrative scenarios (simulated or emulated).
Date: May 14, 2012
Creator: Carvalho, Marco & Ford, Richard
Object Type: Report
System: The UNT Digital Library
Development of Physical Protection Regulations for Rosatom State Corporation Sites under the U.S.-Russian MPC&A Program (open access)

Development of Physical Protection Regulations for Rosatom State Corporation Sites under the U.S.-Russian MPC&A Program

This paper describes issues related to upgrading the physical protection regulatory basis for Rosatom State Corporation sites. It is underlined that most of the regulatory and methodological documents for this subject area have been developed under the U.S.-Russian MPC&A Program. According to the joint management plan developed and agreed upon by the parties in 2005, nearly 50 physical protection documents were identified to be developed, approved and implemented at Rosatom sites by 2012. It is also noted that, on the whole, the plans have been fulfilled.
Date: July 14, 2012
Creator: Izmaylov, Alexander; Babkin, Vladimir; Shemigon, Nikolai N.; O'Brien, Patricia; Wright, Troy L.; Hazel, Michael J. et al.
Object Type: Report
System: The UNT Digital Library
Insights Into the High-Energy Gamma-Ray Emission of Markarian 501 From Extensive Multifrequency Observations in the Fermi Era (open access)

Insights Into the High-Energy Gamma-Ray Emission of Markarian 501 From Extensive Multifrequency Observations in the Fermi Era

None
Date: June 14, 2012
Creator: Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J. et al.
Object Type: Article
System: The UNT Digital Library
Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator Bi2Se3 (open access)

Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator Bi2Se3

Using femtosecond time- and angle-resolved photoemission spectroscopy, we investigated the nonequilibrium dynamics of the topological insulator Bi{sub 2}Se{sub 3}. We studied p-type Bi{sub 2}Se{sub 3}, in which the metallic Dirac surface state and bulk conduction bands are unoccupied. Optical excitation leads to a meta-stable population at the bulk conduction band edge, which feeds a nonequilibrium population of the surface state persisting for >10 ps. This unusually long-lived population of a metallic Dirac surface state with spin texture may present a channel in which to drive transient spin-polarized currents.
Date: March 14, 2012
Creator: Sobota, Jonathan
Object Type: Article
System: The UNT Digital Library
Status of the Super-B Factory Design (open access)

Status of the Super-B Factory Design

None
Date: September 14, 2012
Creator: Wittmer, W.
Object Type: Article
System: The UNT Digital Library
Building 235-F Goldsim Fate And Transport Model (open access)

Building 235-F Goldsim Fate And Transport Model

Savannah River National Laboratory (SRNL) personnel, at the request of Area Completion Projects (ACP), evaluated In-Situ Disposal (ISD) alternatives that are under consideration for deactivation and decommissioning (D&D) of Building 235-F and the Building 294-2F Sand Filter. SRNL personnel developed and used a GoldSim fate and transport model, which is consistent with Musall 2012, to evaluate relative to groundwater protection, ISD alternatives that involve either source removal and/or the grouting of portions or all of 235-F. This evaluation was conducted through the development and use of a Building 235-F GoldSim fate and transport model. The model simulates contaminant release from four 235-F process areas and the 294-2F Sand Filter. In addition, it simulates the fate and transport through the vadose zone, the Upper Three Runs (UTR) aquifer, and the Upper Three Runs (UTR) creek. The model is designed as a stochastic model, and as such it can provide both deterministic and stochastic (probabilistic) results. The results show that the median radium activity concentrations exceed the 5 ?Ci/L radium MCL at the edge of the building for all ISD alternatives after 10,000 years, except those with a sufficient amount of inventory removed. A very interesting result was that grouting was shown …
Date: September 14, 2012
Creator: Taylor, G. A. & Phifer, M. A.
Object Type: Report
System: The UNT Digital Library