Discrete Symmetries on the Light Front and a General Relation connecting Nucleon Electric Dipole and Anomalous Magnetic Moments (open access)

Discrete Symmetries on the Light Front and a General Relation connecting Nucleon Electric Dipole and Anomalous Magnetic Moments

We consider the electric dipole form factor, F{sub 3}(q{sup 2}), as well as the Dirac and Pauli form factors, F{sub 1}(q{sup 2}) and F{sub 2}(q{sup 2}), of the nucleon in the light-front formalism. We derive an exact formula for F{sub 3}(q{sup 2}) to complement those known for F{sub 1}(q{sup 2}) and F{sub 2}(q{sup 2}). We derive the light-front representation of the discrete symmetry transformations and show that time-reversal- and parity-odd effects are captured by phases in the light-front wave functions. We thus determine that the contributions to F{sub 2}(q{sup 2}) and F{sub 3}(q{sup 2}), Fock-state by Fock-state, are related, independent of the fundamental mechanism through which CP violation is generated. Our relation is not specific to the nucleon, but, rather, is true of spin-1/2 systems in general, be they lepton or baryon. The empirical values of the anomalous magnetic moments, in concert with empirical bounds on the associated electric dipole moments, can better constrain theories of CP violation. In particular, we find that the neutron and proton electric dipole moments echo the isospin structure of the anomalous magnetic moments, {kappa}{sup n} {approx} -{kappa}{sup p}.
Date: January 11, 2006
Creator: Brodsky, Stanley J.; Gardner, Susan & Hwang, Dae Sung
System: The UNT Digital Library
Order and disorder in the local and long-range structure of the spin-glass pyrochlore, Tb{sub 2}Mo{sub 2}O{sub 7} (open access)

Order and disorder in the local and long-range structure of the spin-glass pyrochlore, Tb{sub 2}Mo{sub 2}O{sub 7}

To understand the origin of the spin-glass state in molybdate pyrochlores, the structure of Tb{sub 2}Mo{sub 2}O{sub 7} is investigated using two techniques: the long-range lattice structure was measured using neutron powder diffraction (NPD), and local structure information was obtained from the extended x-ray absorption fine structure (EXAFS) technique. While the long-range structure appears generally well ordered, enhanced mean-squared site displacements on the O(1) site and the lack of temperature dependence of the strongly anisotropic displacement parameters for both the Mo and O(1) sites indicate some disorder exists. Likewise, the local structure measurements indicate some Mo-Mo and Tb-O(1) nearest-neighbor disorder exists, similar to that found in the related spin-glass pyrochlore, Y{sub 2}Mo{sub 2}O{sub 7}. Although the freezing temperature in Tb{sub 2}Mo{sub 2}O{sub 7}, 25 K, is slightly higher than in Y{sub 2}Mo{sub 2}O{sub 7}, 22 K, the degree of local pair distance disorder is actually less in Tb{sub 2}Mo{sub 2}O{sub 7}. This apparent contradiction is considered in light of the interactions involved in the freezing process.
Date: February 11, 2011
Creator: Jiang, Yu; Huq, Ashfia; Booth, Corwin H.; Ehlers, Georg; Greedan, John E. & Gardner, Jason S.
System: The UNT Digital Library
An adaptive optics package designed for astronomical use with a laser guide star tuned to an absorption line of atomic sodium (open access)

An adaptive optics package designed for astronomical use with a laser guide star tuned to an absorption line of atomic sodium

We present the design and implementation of a very compact adaptive optic system that senses the return light from a sodium guide-star and controls a deformable mirror and a pointing mirror to compensate atmospheric perturbations in the wavefront. The deformable mirror has 19 electrostrictive actuators and triangular subapertures. The wavefront sensor is a Hartmann sensor with lenslets on triangular centers. The high-bandwidth steering mirror assembly incorporates an analog controller that samples the tilt with an avalanche photodiode quad cell. An {line_integral}/25 imaging leg focuses the light into a science camera that can either obtain long-exposure images or speckle data. In laboratory tests overall Strehl ratios were improved by a factor of 3 when a mylar sheet was used as an aberrator. The crossover frequency at unity gain is 30 Hz.
Date: April 11, 1994
Creator: Salmon, J. T.; Avicola, K. & Brase, J. M.
System: The UNT Digital Library
Amplitude Analysis and Measurement of the Time-dependent CP Asymmetry of B0 to KsKsKs Decays (open access)

Amplitude Analysis and Measurement of the Time-dependent CP Asymmetry of B0 to KsKsKs Decays

We present the first results on the Dalitz-plot structure and improved measurements of the time-dependent CP-violation parameters of the process B{sup 0} {yields} K{sub S}{sup 0}K{sub S}{sup 0}K{sub S}{sup 0} obtained using 468 x 10{sup 6} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The Dalitz-plot structure is probed by a time-integrated amplitude analysis that does not distinguish between B{sup 0} and {bar B}{sup 0} decays. We measure the total inclusive branching fraction {Beta}(B{sup 0} {yields} K{sub S}{sup 0}K{sub S}{sup 0}K{sub S}{sup 0}) = (6.19 {+-} 0.48 {+-} 0.15 {+-} 0.12) x 10{sup -6}, where the first uncertainty is statistical, the second is systematic, and the third represents the Dalitz-plot signal model dependence. We also observe evidence for the intermediate resonant states f{sub 0}(980), f{sub 0}(1710), and f{sub 2}(2010). Their respective product branching fractions are measured to be (2.70{sub -1.19}{sup +1.25} {+-} 0.36 {+-} 1.17) x 10{sup -6}, (0.50{sub -0.24}{sup +0.46} {+-} 0.04 {+-} 0.10) x 10{sup -6}, and (0.54{sub -0.20}{sup +0.21} {+-} 0.03 {+-} 0.52) x 10{sup -6}. Additionally, we determine the mixing-induced CP-violation parameters to be S = -0.94{sub -0.21}{sup +0.24} {+-} 0.06 and C = -0.17 {+-} 0.18 {+-} …
Date: April 11, 2012
Creator: Lees, J. P.
System: The UNT Digital Library
Progress in Long Scale Length Laser-Plasma Interactions (open access)

Progress in Long Scale Length Laser-Plasma Interactions

The first experiments on the National Ignition Facility (NIF) have employed the first four beams to measure propagation and laser backscattering losses in large ignition-size plasmas. Gas-filled targets between 2 mm and 7 mm length have been heated from one side by overlapping the focal spots of the four beams from one quad operated at 351 nm (3{omega}) with a total intensity of 2 x 10{sup 15} W cm{sup -2}. The targets were filled with 1 atm of CO{sub 2} producing of up to 7 mm long homogeneously heated plasmas with densities of n{sub e} = 6 x 10{sup 20} cm{sup -3} and temperatures of T{sub e} = 2 keV. The high energy in a NIF quad of beams of 16kJ, illuminating the target from one direction, creates unique conditions for the study of laser plasma interactions at scale lengths not previously accessible. The propagation through the large-scale plasma was measured with a gated x-ray imager that was filtered for 3.5 keV x rays. These data indicate that the beams interact with the full length of this ignition-scale plasma during the last {approx}1 ns of the experiment. During that time, the full aperture measurements of the stimulated Brillouin scattering and …
Date: November 11, 2003
Creator: Glenzer, S. H.; Arnold, P.; Bardsley, G.; Berger, R. L.; Bonanno, G.; Borger, T. et al.
System: The UNT Digital Library
The First Experiments on the National Ignition Facility (open access)

The First Experiments on the National Ignition Facility

A first set of laser-plasma interaction, hohlraum energetics and hydrodynamic experiments have been performed using the first 4 beams of the National Ignition Facility (NIF), in support of indirect drive Inertial Confinement Fusion (ICF) and High Energy Density Physics (HEDP). In parallel, a robust set of optical and x-ray spectrometers, interferometer, calorimeters and imagers have been activated. The experiments have been undertaken with laser powers and energies of up to 8 TW and 17 kJ in flattop and shaped 1-9 ns pulses focused with various beam smoothing options.
Date: November 11, 2005
Creator: Landen, O. L.; Glenzer, S.; Froula, D.; Dewald, E.; Suter, L. J.; Schneider, M. et al.
System: The UNT Digital Library
Effects of landscape disturbance on ecohydrologic systems (open access)

Effects of landscape disturbance on ecohydrologic systems

None
Date: September 11, 2002
Creator: Newman, Brent D.; Allen, Craig Daniel; Breshears, David D. & Wilson, Cathy J.
System: The UNT Digital Library
Factor structure of the Torrance Tests of Creative Thinking Figural Form A in Kiswahili speaking children: Multidimensionality and influences on creative behavior (open access)

Factor structure of the Torrance Tests of Creative Thinking Figural Form A in Kiswahili speaking children: Multidimensionality and influences on creative behavior

This article provides evidence for the valid use of the Torrance Tests of Creative Thinking (TTCT) in sub-Saharan Africa.
Date: November 19, 2016
Creator: Humble, Steve; Dixon, Pauline & Mpofu, Elias
System: The UNT Digital Library
Ultrasonic characterization of synthetic soils for application to near surface geophysics (open access)

Ultrasonic characterization of synthetic soils for application to near surface geophysics

None
Date: November 11, 1999
Creator: Berge, P; Bonner, B P; Boro, C; Hardy, E; Ruddle, C & Trombino, C
System: The UNT Digital Library
Advances in Scientific Visualization (open access)

Advances in Scientific Visualization

This paper discusses scientific visualization of scalar and vector fields, particularly relating to clouds and climate modeling. One cloud rendering method applies a 3-D texture to cloudiness contour surfaces, to simulate a view from outer space. The texture is advected by the wind flow, so that it follows the cloud motion. Another technique simulates multiple scattering of incident light from the sun and sky. This paper also presents a simulation of the microscopic cross-bridge motion which powers muscle contraction. It was rendered by ray-tracing contour surfaces of summed Gaussian ellipsoids approximating the actin and myosin protein shapes.
Date: January 11, 1995
Creator: Max, N. & Crawfis, R.
System: The UNT Digital Library
Status of cross-section data for gas production from vanadium and {sup 26}AL from silicon carbide in a D-T fusion reactor. (open access)

Status of cross-section data for gas production from vanadium and {sup 26}AL from silicon carbide in a D-T fusion reactor.

Current designs of fusion-reactor systems seek to use radiation-resistant, low-activation materials that support long service lifetimes and minimize radioactive-waste problems after decommissioning. Reliable assessment of fusion materials performance requires accurate neutron-reaction cross sections and radioactive-decay constants. The problem areas usually involve cross sections since decay parameters tend to be better known. The present study was motivated by two specific questions: (i) Why are the {sup 51}V(n,np){sup 50}Ti cross section values in the ENDF/B-VI library so large (a gas production issue)? (ii) How well known are the cross sections associated with producing 7.4 x 10{sup 5} y {sup 26}Al in silicon carbide by the process {sup 28}Si(n,np+d){sup 27} Al(n,2n){sup 26}Al (a long-lived radioactivity issue)? The energy range 14-15 MeV of the D-T fusion neutrons is emphasized. Cross-section error bars are needed so that uncertainties in the gas and radioactivity generated over the lifetime of a reactor can be estimated. We address this issue by comparing values obtained from prominent evaluated cross-section libraries. Small differences between independent evaluations indicate that a physical quantity is well known while the opposite signals a problem. Hydrogen from {sup 51}V(n,p){sup 51}Ti and helium from {sup 51}V(n,{alpha}){sup 48}Sc are also important sources of gas in vanadium, so …
Date: August 11, 1998
Creator: Gomes, I. C.
System: The UNT Digital Library
Extragalactic Background Light from Hierarchical Galaxy Formation: Gamma-ray Attenuation up to the Epoch of Cosmic Reionization and the First Stars (open access)

Extragalactic Background Light from Hierarchical Galaxy Formation: Gamma-ray Attenuation up to the Epoch of Cosmic Reionization and the First Stars

None
Date: April 11, 2013
Creator: Inoue, Yoshiyuki; /KIPAC, Menlo Park /SLAC; Inoue, Susumu; /Heidelberg, Max Planck Inst. /Tokyo U., ICRR; Kobayashi, Masakazu A.R.; U., /Ehime et al.
System: The UNT Digital Library
New Developments in Measurements of CP Violation (open access)

New Developments in Measurements of CP Violation

We present several alternative techniques used by the BABAR Collaboration in order to measure the Unitarity Triangle angle {gamma}. We also present the results of two searches designed to improve the measurements of sin(2{beta}) using penguin B decay modes by reducing the hadronic corrections uncertainties.
Date: August 11, 2006
Creator: Benelli, Gabriele
System: The UNT Digital Library
Perception of Falls and Confidence in Self-Management of Falls among Older Adults (open access)

Perception of Falls and Confidence in Self-Management of Falls among Older Adults

This article investigates the relative contribution of confidence of self-management in falls (CSMoF) in relation to fall risk self-perceptions while controlling for demographics and self-reported health and functioning. The joint effects of perception of falls and fear of falls likely explain CSMoF among older adults more than physical functional indicators. Fall prevention programs for older adults should prioritize to address modifiable subjective factors of fall perceptions, fear of falls, and CSMoF across health and functioning statuses.
Date: December 11, 2019
Creator: Li, Qiwei; Mpofu, Elias; Yin, Cheng & Turner, K. Whisnant (Keith Whisnant)
System: The UNT Digital Library
Dark Matter and Baryons in the Most X-ray Luminous and Merging Galaxy Cluster RX (open access)

Dark Matter and Baryons in the Most X-ray Luminous and Merging Galaxy Cluster RX

None
Date: April 11, 2008
Creator: Bradac, Marusa; Schrabback, Tim; Erben, Thomas; McCourt, Michael; Million, Evan; Mantz, Adam et al.
System: The UNT Digital Library
Search for Diphoton Events with Large Missing Transverse Energy in 7 TeV Proton-Proton Collisions with the ATLAS Detector (open access)