ADVANCED COMPOSITE WIND TURBINE BLADE DESIGN BASED ON DURABILITY AND DAMAGE TOLERANCE (open access)

ADVANCED COMPOSITE WIND TURBINE BLADE DESIGN BASED ON DURABILITY AND DAMAGE TOLERANCE

The objective of the program was to demonstrate and verify Certification-by-Analysis (CBA) capability for wind turbine blades made from advanced lightweight composite materials. The approach integrated durability and damage tolerance analysis with robust design and virtual testing capabilities to deliver superior, durable, low weight, low cost, long life, and reliable wind blade design. The GENOA durability and life prediction software suite was be used as the primary simulation tool. First, a micromechanics-based computational approach was used to assess the durability of composite laminates with ply drop features commonly used in wind turbine applications. Ply drops occur in composite joints and closures of wind turbine blades to reduce skin thicknesses along the blade span. They increase localized stress concentration, which may cause premature delamination failure in composite and reduced fatigue service life. Durability and damage tolerance (D&DT) were evaluated utilizing a multi-scale micro-macro progressive failure analysis (PFA) technique. PFA is finite element based and is capable of detecting all stages of material damage including initiation and propagation of delamination. It assesses multiple failure criteria and includes the effects of manufacturing anomalies (i.e., void, fiber waviness). Two different approaches have been used within PFA. The first approach is Virtual Crack Closure Technique …
Date: February 16, 2012
Creator: Abumeri, Galib & Abdi, Frank
Object Type: Report
System: The UNT Digital Library
Search for Dark Matter Satellites Using the FERMI-LAT (open access)

Search for Dark Matter Satellites Using the FERMI-LAT

Numerical simulations based on the {Lambda}CDM model of cosmology predict a large number of as yet unobserved Galactic dark matter satellites. We report the results of a Large Area Telescope (LAT) search for these satellites via the {gamma}-ray emission expected from the annihilation of weakly interacting massive particle (WIMP) dark matter. Some dark matter satellites are expected to have hard {gamma}-ray spectra, finite angular extents, and a lack of counterparts at other wavelengths. We sought to identify LAT sources with these characteristics, focusing on {gamma}-ray spectra consistent with WIMP annihilation through the b{bar b} channel. We found no viable dark matter satellite candidates using one year of data, and we present a framework for interpreting this result in the context of numerical simulations to constrain the velocity-averaged annihilation cross section for a conventional 100 GeV WIMP annihilating through the b{bar b} channel.
Date: August 16, 2012
Creator: Ackermann, M.; Albert, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D. et al.
Object Type: Article
System: The UNT Digital Library
The Luminosity Function of Fermi-detected Flat-Spectrum Radio Quasars (open access)

The Luminosity Function of Fermi-detected Flat-Spectrum Radio Quasars

Fermi has provided the largest sample of {gamma}-ray selected blazars to date. In this work we use a complete sample of FSRQs detected during the first year of operation to determine the luminosity function (LF) and its evolution with cosmic time. The number density of FSRQs grows dramatically up to redshift {approx}0.5-2.0 and declines thereafter. The redshift of the peak in the density is luminosity dependent, with more luminous sources peaking at earlier times; thus the LF of {gamma}-ray FSRQs follows a luminosity-dependent density evolution similarly to that of radio-quiet AGN. Also using data from the Swift Burst Alert Telescope we derive the average spectral energy distribution of FSRQs in the 10 keV-100GeV band and show that there is no correlation of the peak {gamma}-ray luminosity with {gamma}-ray peak frequency. The coupling of the SED and LF allows us to predict that the contribution of FSRQs to the Fermi isotropic {gamma}-ray background is 9.3{sub -1.0}{sup +1.6}% ({+-}3% systematic uncertainty) in the 0.1-100GeV band. Finally we determine the LF of unbeamed FSRQs, finding that FSRQs have an average Lorentz factor of {gamma} = 11.7{sub -2.2}{sup +3.3}, that most are seen within 5{sup o} of the jet axis, and that they represent …
Date: April 16, 2012
Creator: Ajello, M.; Shaw, M. S.; Romani, R. W.; Dermer, C. D.; Costamante, L.; King, O. G. et al.
Object Type: Article
System: The UNT Digital Library
2d Affine XY-Spin Model/4d Gauge Theory Duality and Deconfinement (open access)

2d Affine XY-Spin Model/4d Gauge Theory Duality and Deconfinement

We introduce a duality between two-dimensional XY-spin models with symmetry-breaking perturbations and certain four-dimensional SU(2) and SU(2) = Z{sub 2} gauge theories, compactified on a small spatial circle R{sup 1,2} x S{sup 1}, and considered at temperatures near the deconfinement transition. In a Euclidean set up, the theory is defined on R{sup 2} x T{sup 2}. Similarly, thermal gauge theories of higher rank are dual to new families of 'affine' XY-spin models with perturbations. For rank two, these are related to models used to describe the melting of a 2d crystal with a triangular lattice. The connection is made through a multi-component electric-magnetic Coulomb gas representation for both systems. Perturbations in the spin system map to topological defects in the gauge theory, such as monopole-instantons or magnetic bions, and the vortices in the spin system map to the electrically charged W-bosons in field theory (or vice versa, depending on the duality frame). The duality permits one to use the two-dimensional technology of spin systems to study the thermal deconfinement and discrete chiral transitions in four-dimensional SU(N{sub c}) gauge theories with n{sub f} {ge} 1 adjoint Weyl fermions.
Date: August 16, 2012
Creator: Anber, Mohamed M.; Poppitz, Erich; U., /Toronto; Unsal, Mithat & /SLAC /Stanford U., Phys. Dept. /San Francisco State U.
Object Type: Article
System: The UNT Digital Library
Crisis In Mali (open access)

Crisis In Mali

This report discusses the West African country of Mali that faces multiple overlapping crises. The country’s political leadership has been uncertain and disputed since a military coup on March 22, 2012, overthrew a democratically elected government in the capital, Bamako.
Date: August 16, 2012
Creator: Arieff, Alexis & Johnson, Kelly
Object Type: Report
System: The UNT Digital Library
High Statistics Study of Nearby Type 1a Supernovae. QUEST Camera Short Term Maintenance: Final Technical Report (open access)

High Statistics Study of Nearby Type 1a Supernovae. QUEST Camera Short Term Maintenance: Final Technical Report

The Quest Camera was installed at the Palomar Obervatory in California. The camera was used to carry out a survey of low redshift Type 1a supernovae.The purpose of this DOE grant was to perform short term maintenance on the QUEST camera.
Date: October 16, 2012
Creator: Baltay, Charles
Object Type: Report
System: The UNT Digital Library
Results For The First Quarter 2012 Tank 50 WAC Slurry Sample: Chemical And Radionuclide Contaminant Results (open access)

Results For The First Quarter 2012 Tank 50 WAC Slurry Sample: Chemical And Radionuclide Contaminant Results

This report details the chemical and radionuclide contaminant results for the characterization of the 2012 First Quarter sampling of Tank 50 for the Saltstone Waste Acceptance Criteria (WAC). Information from this characterization will be used by Waste Solidification Engineering (WSE) to support the transfer of low-level aqueous waste from Tank 50 to the Salt Feed Tank in the Saltstone Facility in Z-Area, where the waste will be immobilized. This information is also used to update the Tank 50 Waste Characterization System. The following conclusions are drawn from the analytical results provided in this memorandum: The concentrations of the reported chemical and radioactive contaminants were less than their respective WAC targets or limits unless noted; The reported detection limit for {sup 94}Nb is above the requested limit but below the estimated limit; {sup 247}Cm and {sup 249}Cf are above the requested limits. However, they are below the limits established; The reported detection limit for Norpar 13 is greater than the limit from the WAC; The reported detection limit for Isopar L is greater than the limit from WAC; Isopar L and Norpar 13 have limited solubility in aqueous solutions making it difficult to obtain consistent and reliable sub-samples; The values reported …
Date: July 16, 2012
Creator: Bannochie, C. J.
Object Type: Report
System: The UNT Digital Library
REVIEW OF PARTICLE PHYSICS (open access)

REVIEW OF PARTICLE PHYSICS

This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2658 new measurements from 644 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 112 reviews are many that are new or heavily revised including those on Heavy-Quark and Soft-Collinear Effective Theory, Neutrino Cross Section Measurements, Monte Carlo Event Generators, Lattice QCD, Heavy Quarkonium Spectroscopy, Top Quark, Dark Matter, V{sub cb} & V{sub ub}, Quantum Chromodynamics, High-Energy Collider Parameters, Astrophysical Constants, Cosmological Parameters, and Dark Matter. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov.
Date: July 16, 2012
Creator: Beringer, Juerg
Object Type: Article
System: The UNT Digital Library
Vibration Model Validation for Linear Collider Detector Platforms (open access)

Vibration Model Validation for Linear Collider Detector Platforms

The ILC and CLIC reference designs incorporate reinforced-concrete platforms underneath the detectors so that the two detectors can each be moved onto and off of the beamline in a Push-Pull configuration. These platforms could potentially amplify ground vibrations, which would reduce luminosity. In this paper we compare vibration models to experimental data on reinforced concrete structures, estimate the impact on luminosity, and summarize implications for the design of a reinforced concrete platform for the ILC or CLIC detectors.
Date: May 16, 2012
Creator: Bertsche, Kirk; Amann, J. W.; Markiewicz, T. W.; Oriunno, M.; Weidemann, A. & White, G.
Object Type: Article
System: The UNT Digital Library
International Family Planning Programs: Issues for Congress (open access)

International Family Planning Programs: Issues for Congress

This report looks at how the debate over family planning within the U.S. is spilling over to U.S.-funded family planning programs abroad.
Date: March 16, 2012
Creator: Blanchfield, Luisa
Object Type: Report
System: The UNT Digital Library
Blinn College Requests for Legislative Appropriations: Fiscal Years 2014 and 2015 (open access)

Blinn College Requests for Legislative Appropriations: Fiscal Years 2014 and 2015

Report submitted by Blinn College containing background information on the commission, and summaries of requests for appropriations and expenditures for the fiscal years 2014 and 2015 with supporting documentation.
Date: August 16, 2012
Creator: Blinn College
Object Type: Book
System: The Portal to Texas History
NEAMS Update. Quarterly Report for October - December 2011. (open access)

NEAMS Update. Quarterly Report for October - December 2011.

The Advanced Modeling and Simulation Office within the DOE Office of Nuclear Energy (NE) has been charged with revolutionizing the design tools used to build nuclear power plants during the next 10 years. To accomplish this, the DOE has brought together the national laboratories, U.S. universities, and the nuclear energy industry to establish the Nuclear Energy Advanced Modeling and Simulation (NEAMS) Program. The mission of NEAMS is to modernize computer modeling of nuclear energy systems and improve the fidelity and validity of modeling results using contemporary software environments and high-performance computers. NEAMS will create a set of engineering-level codes aimed at designing and analyzing the performance and safety of nuclear power plants and reactor fuels. The truly predictive nature of these codes will be achieved by modeling the governing phenomena at the spatial and temporal scales that dominate the behavior. These codes will be executed within a simulation environment that orchestrates code integration with respect to spatial meshing, computational resources, and execution to give the user a common 'look and feel' for setting up problems and displaying results. NEAMS is building upon a suite of existing simulation tools, including those developed by the federal Scientific Discovery through Advanced Computing and …
Date: February 16, 2012
Creator: Bradley, K. (Nuclear Engineering Division)
Object Type: Report
System: The UNT Digital Library
Hot Particle and Turbulent Transport Effects on Resistive Instabilities (open access)

Hot Particle and Turbulent Transport Effects on Resistive Instabilities

This research project included two main thrusts; energetic particle effects on resistive MHD modes in tokamaks, and turbulence interactions with tearing modes in simplified geometry.
Date: October 16, 2012
Creator: Brennan, Dylan P.
Object Type: Report
System: The UNT Digital Library
Physics Opportunities of a Fixed-Target Experiment using the LHC Beams (open access)

Physics Opportunities of a Fixed-Target Experiment using the LHC Beams

We outline the many physics opportunities offered by a multi-purpose fixed-target experiment using the proton and lead-ion beams of the LHC extracted by a bent crystal. In a proton run with the LHC 7-TeV beam, one can analyze pp, pd and pA collisions at center-of-mass energy {radical}s{sub NN} {approx_equal} 115 GeV and even higher using the Fermi motion of the nucleons in a nuclear target. In a lead run with a 2.76 TeV-per-nucleon beam, {radical}s{sub NN} is as high as 72 GeV. Bent crystals can be used to extract about 5 x 10{sup 8} protons/sec; the integrated luminosity over a year reaches 0.5 fb{sup -1} on a typical 1 cm-long target without nuclear species limitation. We emphasize that such an extraction mode does not alter the performance of the collider experiments at the LHC. By instrumenting the target-rapidity region, gluon and heavy-quark distributions of the proton and the neutron can be accessed at large x and even at x larger than unity in the nuclear case. Single diffractive physics and, for the first time, the large negative-xF domain can be accessed. The nuclear target-species versatility provides a unique opportunity to study nuclear matter versus the features of the hot and …
Date: March 16, 2012
Creator: Brodsky, S.J.; /SLAC; Fleuret, F.; Polytechnique, /Ecole; Hadjidakis, C.; Lansberg, J.P. et al.
Object Type: Article
System: The UNT Digital Library
The Impact of Intrinsic Heavy Quark Distributions in the Proton on New Physics Searches at the High Intensity Frontier (open access)

The Impact of Intrinsic Heavy Quark Distributions in the Proton on New Physics Searches at the High Intensity Frontier

The possibility of an intense proton facility, at 'Project X' or elsewhere, will provide many new opportunities for searches for physics beyond the Standard Model. A Project X can serve a yet broader role in the search for new physics, and in this note we highlight the manner in which thus-enabled studies of the flavor structure of the proton, particularly of its intrinsic heavy quark content, facilitate other direct and indirect searches for new physics. Intrinsic heavy quarks in both light and heavy hadrons play a key role in searches for physics BSM with hadrons - and their study at the Intensity Frontier may prove crucial to establishing its existence.
Date: February 16, 2012
Creator: Brodsky, Stanley & Gardner, Susan
Object Type: Article
System: The UNT Digital Library
Atoms in Flight: The Remarkable Connections between Atomic and Hadronic Physics (open access)

Atoms in Flight: The Remarkable Connections between Atomic and Hadronic Physics

Atomic physics and hadron physics are both based on Yang Mills gauge theory; in fact, quantum electrodynamics can be regarded as the zero-color limit of quantum chromodynamics. I review a number of areas where the techniques of atomic physics provide important insight into the theory of hadrons in QCD. For example, the Dirac-Coulomb equation, which predicts the spectroscopy and structure of hydrogenic atoms, has an analog in hadron physics in the form of light-front relativistic equations of motion which give a remarkable first approximation to the spectroscopy, dynamics, and structure of light hadrons. The renormalization scale for the running coupling, which is unambiguously set in QED, leads to a method for setting the renormalization scale in QCD. The production of atoms in flight provides a method for computing the formation of hadrons at the amplitude level. Conversely, many techniques which have been developed for hadron physics, such as scaling laws, evolution equations, and light-front quantization have equal utility for atomic physics, especially in the relativistic domain. I also present a new perspective for understanding the contributions to the cosmological constant from QED and QCD.
Date: February 16, 2012
Creator: Brodsky, Stanley J.
Object Type: Article
System: The UNT Digital Library
Transversity from First Principles in QCD (open access)

Transversity from First Principles in QCD

Transversity observables, such as the T-odd Sivers single-spin asymmetry measured in deep inelastic lepton scattering on polarized protons and the distributions which are measured in deeply virtual Compton scattering, provide important constraints on the fundamental quark and gluon structure of the proton. In this talk I discuss the challenge of computing these observables from first principles; i.e.; quantum chromodynamics, itself. A key step is the determination of the frame-independent light-front wavefunctions (LFWFs) of hadrons - the QCD eigensolutions which are analogs of the Schroedinger wavefunctions of atomic physics. The lensing effects of initial-state and final-state interactions, acting on LFWFs with different orbital angular momentum, lead to T-odd transversity observables such as the Sivers, Collins, and Boer-Mulders distributions. The lensing effect also leads to leading-twist phenomena which break leading-twist factorization such as the breakdown of the Lam-Tung relation in Drell-Yan reactions. A similar rescattering mechanism also leads to diffractive deep inelastic scattering, as well as nuclear shadowing and non-universal antishadowing. It is thus important to distinguish 'static' structure functions, the probability distributions computed the target hadron's light-front wavefunctions, versus 'dynamical' structure functions which include the effects of initial- and final-state rescattering. I also discuss related effects such as the J = …
Date: February 16, 2012
Creator: Brodsky, Stanley J. & /SLAC /Southern Denmark U., CP3-Origins
Object Type: Article
System: The UNT Digital Library
Pair Production Constraints on Superluminal Neutrinos Revisited (open access)

Pair Production Constraints on Superluminal Neutrinos Revisited

We revisit the pair creation constraint on superluminal neutrinos considered by Cohen and Glashow in order to clarify which types of superluminal models are constrained. We show that a model in which the superluminal neutrino is effectively light-like can evade the Cohen-Glashow constraint. In summary, any model for which the CG pair production process operates is excluded because such timelike neutrinos would not be detected by OPERA or other experiments. However, a superluminal neutrino which is effectively lightlike with fixed p{sup 2} can evade the Cohen-Glashow constraint because of energy-momentum conservation. The coincidence involved in explaining the SN1987A constraint certainly makes such a picture improbable - but it is still intrinsically possible. The lightlike model is appealing in that it does not violate Lorentz symmetry in particle interactions, although one would expect Hughes-Drever tests to turn up a violation eventually. Other evasions of the CG constraints are also possible; perhaps, e.g., the neutrino takes a 'short cut' through extra dimensions or suffers anomalous acceleration in matter. Irrespective of the OPERA result, Lorentz-violating interactions remain possible, and ongoing experimental investigation of such possibilities should continue.
Date: February 16, 2012
Creator: Brodsky, Stanley J. & Gardner, Susan
Object Type: Article
System: The UNT Digital Library
Scale Setting Using the Extended Re normalization Group and the Principle of Maximal Conformality: the QCD Coupling at Four Loops (open access)

Scale Setting Using the Extended Re normalization Group and the Principle of Maximal Conformality: the QCD Coupling at Four Loops

A key problem in making precise perturbative QCD predictions is to set the proper renormalization scale of the running coupling. The extended renormalization group equations, which express the invariance of physical observables under both the renormalization scale- and scheme-parameter transformations, provide a convenient way for estimating the scale- and scheme-dependence of the physical process. In this paper, we present a solution for the scale-equation of the extended renormalization group equations at the four-loop level. Using the principle of maximum conformality (PMC)/Brodsky-Lepage-Mackenzie (BLM) scale-setting method, all non-conformal {beta}{sub i} terms in the perturbative expansion series can be summed into the running coupling, and the resulting scale-fixed predictions are independent of the renormalization scheme. Different schemes lead to different effective PMC/BLM scales, but the final results are scheme independent. Conversely, from the requirement of scheme independence, one not only can obtain scheme-independent commensurate scale relations among different observables, but also determine the scale displacements among the PMC/BLM scales which are derived under different schemes. In principle, the PMC/BLM scales can be fixed order-by-order, and as a useful reference, we present a systematic and scheme-independent procedure for setting PMC/BLM scales up to NNLO. An explicit application for determining the scale setting of R{sub …
Date: February 16, 2012
Creator: Brodsky, Stanley J. & Wu, Xing-Gang
Object Type: Article
System: The UNT Digital Library
AdS/QCD, Light-Front Holography, and Sublimated Gluons (open access)

AdS/QCD, Light-Front Holography, and Sublimated Gluons

The gauge/gravity duality leads to a simple analytical and phenomenologically compelling nonperturbative approximation to the full light-front QCD Hamiltonian - 'Light-Front Holography', which provides a Lorentz-invariant first-approximation to QCD, and successfully describes the spectroscopy of light-quark meson and baryons, their elastic and transition form factors, and other hadronic properties. The bound-state Schroedinger and Dirac equations of the soft-wall AdS/QCD model predict linear Regge trajectories which have the same slope in orbital angular momentum L and radial quantum number n for both mesons and baryons. Light-front holography connects the fifth-dimensional coordinate of AdS space z to an invariant impact separation variable {zeta} in 3+1 space at fixed light-front time. A key feature is the determination of the frame-independent light-front wavefunctions of hadrons - the relativistic analogs of the Schroedinger wavefunctions of atomic physics which allow one to compute form factors, transversity distributions, spin properties of the valence quarks, jet hadronization, and other hadronic observables. One thus obtains a one-parameter color-confining model for hadron physics at the amplitude level. AdS/QCD also predicts the form of the non-perturbative effective coupling {alpha}{sub s}{sup AdS} (Q) and its {beta}-function with an infrared fixed point which agrees with the effective coupling a{sub g1} (Q{sup 2}) extracted …
Date: February 16, 2012
Creator: Brodsky, Stanley J. & de Teramond, Guy F.
Object Type: Article
System: The UNT Digital Library
AdS/QCD and Applications of Light-Front Holography (open access)

AdS/QCD and Applications of Light-Front Holography

Light-Front Holography leads to a rigorous connection between hadronic amplitudes in a higher dimensional anti-de Sitter (AdS) space and frame-independent light-front wavefunctions of hadrons in 3 + 1 physical space-time, thus providing a compelling physical interpretation of the AdS/CFT correspondence principle and AdS/QCD, a useful framework which describes the correspondence between theories in a modified AdS5 background and confining field theories in physical space-time. To a first semiclassical approximation, where quantum loops and quark masses are not included, this approach leads to a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time. The internal structure of hadrons is explicitly introduced and the angular momentum of the constituents plays a key role. We give an overview of the light-front holographic approach to strongly coupled QCD. In particular, we study the photon-to-meson transition form factors (TFFs) F{sub M{gamma}}(Q{sup 2}) for {gamma}{gamma}* {yields} M using light-front holographic methods. The results for the TFFs for the {eta} and {eta}' mesons are also presented. Some …
Date: February 16, 2012
Creator: Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; Cao, Fu-Guang; U., /Massey; de Teramond, Guy F. & U., /Costa Rica
Object Type: Article
System: The UNT Digital Library
Light-Front Holographic QCD (open access)

Light-Front Holographic QCD

The relation between the hadronic short-distance constituent quark and gluon particle limit and the long-range confining domain is yet one of the most challenging aspects of particle physics due to the strong coupling nature of Quantum Chromodynamics, the fundamental theory of the strong interactions. The central question is how one can compute hadronic properties from first principles; i.e., directly from the QCD Lagrangian. The most successful theoretical approach thus far has been to quantize QCD on discrete lattices in Euclidean space-time. Lattice numerical results follow from computation of frame-dependent moments of distributions in Euclidean space and dynamical observables in Minkowski spacetime, such as the time-like hadronic form factors, are not amenable to Euclidean lattice computations. The Dyson-Schwinger methods have led to many important insights, such as the infrared fixed point behavior of the strong coupling constant, but in practice, the analyses are limited to ladder approximation in Landau gauge. Baryon spectroscopy and the excitation dynamics of nucleon resonances encoded in the nucleon transition form factors can provide fundamental insight into the strong-coupling dynamics of QCD. New theoretical tools are thus of primary interest for the interpretation of the results expected at the new mass scale and kinematic regions accessible to …
Date: February 16, 2012
Creator: Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F. & U., /Costa Rica
Object Type: Article
System: The UNT Digital Library
Light-Front Holography, Light-Front Wavefunctions, and Novel QCD Phenomena (open access)

Light-Front Holography, Light-Front Wavefunctions, and Novel QCD Phenomena

Light-Front Holography is one of the most remarkable features of the AdS/CFT correspondence. In spite of its present limitations it provides important physical insights into the nonperturbative regime of QCD and its transition to the perturbative domain. This novel framework allows hadronic amplitudes in a higher dimensional anti-de Sitter (AdS) space to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time. The model leads to an effective confining light-front QCD Hamiltonian and a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time and determines the off-shell dynamics of the bound-state wavefunctions, and thus the fall-off as a function of the invariant mass of the constituents. The soft-wall holographic model modified by a positive-sign dilaton metric, leads to a remarkable one-parameter description of nonperturbative hadron dynamics - a semi-classical frame-independent first approximation to the spectra and light-front wavefunctions of meson and baryons. The model predicts a Regge spectrum of linear trajectories with the same slope in the leading orbital …
Date: February 16, 2012
Creator: Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F. & U., /Costa Rica
Object Type: Article
System: The UNT Digital Library
A Non-Invasive Energy/Angle Diagnostic for Charged Particle Beams (open access)

A Non-Invasive Energy/Angle Diagnostic for Charged Particle Beams

A diagnostic for charged particle beams based on Compton scattering is presented. The particular case of an electron beam is treated in detail relativistically.
Date: March 16, 2012
Creator: Christensen, C. R.
Object Type: Article
System: The UNT Digital Library