Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 9 of 9
Full-Text Articles in Physics
Two Nucleon Systems At M(Pi) Similar To 450 Mev From Lattice Qcd, Kostas Orginos, Assumpta Parreño, Martin J. Savage, Silas R. Beane, Et Al.
Two Nucleon Systems At M(Pi) Similar To 450 Mev From Lattice Qcd, Kostas Orginos, Assumpta Parreño, Martin J. Savage, Silas R. Beane, Et Al.
Arts & Sciences Articles
Nucleon-nucleon systems are studied with lattice quantum chromodynamics at a pion mass of m(pi) similar to 450 MeV in three spatial volumes using n(f) = 2 + 1 flavors of light quarks. At the quark masses employed in this work, the deuteron binding energy is calculated to be B-d = 14.4(-2.6)(+3.2) MeV, while the dineutron is bound by B-nn = 12.5(-5.0)(+3.0) MeV. Over the range of energies that are studied, the S-wave scattering phase shifts calculated in the S-1(0) and S-3(1)-D-3(1) channels are found to be similar to those in nature, and indicate repulsive short-range components of the interactions, consistent …
Particle Transport In Low-Collisionality H-Mode Plasmas On Diii-D, Saskia Mordijck, X. Wang, E. J. Doyle, T. L. Rhodes, Et Al.
Particle Transport In Low-Collisionality H-Mode Plasmas On Diii-D, Saskia Mordijck, X. Wang, E. J. Doyle, T. L. Rhodes, Et Al.
Arts & Sciences Articles
In this paper we show that changing from an ion temperature gradient (ITG) to a trapped electron mode (TEM) dominant turbulence regime (based on linear gyrokinetic simulations) results experimentally in a strong density pump-out (defined as a reduction in line-averaged density) in low collisionality, low power H-mode plasmas. We vary the turbulence drive by changing the heating from predominantly ion heated using neutral beam injection to electron heated using electron cyclotron heating, which changes the T-e/T-i ratio and the temperature gradients. Perturbed gas puff experiments show an increase in transport outside rho = 0.6, through a strong increase in the …
Phase Transition In Bulk Single Crystals And Thin Films Of Vo2 By Nanoscale Infrared Spectroscopy And Imaging, Mengkun Liu, Aaron J. Sternbach, (...), M. M. Qazilbash, Et Al.
Phase Transition In Bulk Single Crystals And Thin Films Of Vo2 By Nanoscale Infrared Spectroscopy And Imaging, Mengkun Liu, Aaron J. Sternbach, (...), M. M. Qazilbash, Et Al.
Arts & Sciences Articles
We have systematically studied a variety of vanadium dioxide (VO2) crystalline forms, including bulk single crystals and oriented thin films, using infrared (IR) near-field spectroscopic imaging techniques. By measuring the IR spectroscopic responses of electrons and phonons in VO2 with sub-grain-size spatial resolution (similar to 20 nm), we show that epitaxial strain in VO2 thin films not only triggers spontaneous local phase separations, but also leads to intermediate electronic and lattice states that are intrinsically different from those found in bulk. Generalized rules of strain-and symmetry-dependent mesoscopic phase inhomogeneity are also discussed. These results set the stage for a comprehensive …
Modification Of Electronic Structure In Compressively Strained Vanadium Dioxide Films, T. J. Huffman, Peng Xu, A. J. Hollingshad, M. M. Qazilbash, Et Al.
Modification Of Electronic Structure In Compressively Strained Vanadium Dioxide Films, T. J. Huffman, Peng Xu, A. J. Hollingshad, M. M. Qazilbash, Et Al.
Arts & Sciences Articles
Vanadium dioxide (VO2) undergoes a phase transition between an insulating monoclinic phase and a conducting rutile phase. Like other correlated electron systems, the properties of VO2 can be extremely sensitive to small changes in external parameters such as strain. In this paper, we investigate a compressively strained VO2 film grown on (001) quartz substrate in which the phase transition temperature (T-c) has been depressed to 325 K from the bulk value of 340 K. Infrared and optical spectroscopy reveals that the lattice dynamics of this strained film are similar to unstrained VO2. However, some of the electronic interband transitions of …
Precision Measurement Of The P(E,E ' P)Pi(0) Reaction At Threshold, K. Chirapatpimol, (...), David S. Armstrong, Et Al.
Precision Measurement Of The P(E,E ' P)Pi(0) Reaction At Threshold, K. Chirapatpimol, (...), David S. Armstrong, Et Al.
Arts & Sciences Articles
New results are reported from a measurement of pi(0) electroproduction near threshold using the p(e , e'p)pi(0) reaction. The experiment was designed to determine precisely the energy dependence of s- and p-wave electromagnetic multipoles as a stringent test of the predictions of chiral perturbation theory (ChPT). The data were taken with an electron beam energy of 1192 MeV using a two-spectrometer setup in Hall A at Jefferson Lab. For the first time, complete coverage of the. phi*(pi) and. theta*(pi) angles in the p pi(0) center of mass was obtained for invariant energies above threshold from 0.5 up to 15 MeV. …
Precision Measurements Of A^N1 In The Deep Inelastic Regime, Jefferson Lab Hall A Collaboration, Todd Averett
Precision Measurements Of A^N1 In The Deep Inelastic Regime, Jefferson Lab Hall A Collaboration, Todd Averett
Arts & Sciences Articles
We have performed precision measurements of the double-spin virtual-photon asymmetry A1 on the neutron in the deep inelastic scattering regime, using an open-geometry, large-acceptance spectrometer and a longitudinally and transversely polarized 3He target. Our data cover a wide kinematic range 0.277 ≤ x ≤ 0.548 at an average Q 2 value of 3.078 (GeV/c)2, doubling the available high-precision neutron data in this x range. We have combined our results with world data on proton targets to make a leading-order extraction of the ratio of polarized-to-unpolarized parton distribution functions for up quarks and for down quarks in the same kinematic range. …
The Q(Weak) Experimental Apparatus, T. Allison, (...), David S. Armstrong, Et Al.
The Q(Weak) Experimental Apparatus, T. Allison, (...), David S. Armstrong, Et Al.
Arts & Sciences Articles
The Jefferson Lab experiment determined the weak charge of the proton by measuring the parity-violating elastic scattering asymmetry of longitudinally polarized electrons from an unpolarized liquid hydrogen target at small momentum transfer. A custom apparatus was designed for this experiment to meet the technical challenges presented by the smallest and most precise (e) over right arrowp asymmetry ever measured. Technical milestones were achieved at Jefferson Lab in target power, beam current, beam helicity reversal rate, polarimetry, detected rates, and control of helicity-correlated beam properties. The experiment employed 180 mu A of 89% longitudinally polarized electrons whose helicity was reversed 960 …
Locally Smeared Operator Product Expansions In Scalar Field Theory, Christopher J. Monahan, Kostas Orginos
Locally Smeared Operator Product Expansions In Scalar Field Theory, Christopher J. Monahan, Kostas Orginos
Arts & Sciences Articles
We propose a new locally smeared operator product expansion to decompose nonlocal operators in terms of a basis of smeared operators. The smeared operator product expansion formally connects nonperturbative matrix elements determined numerically using lattice field theory to matrix elements of nonlocal operators in the continuum. These nonperturbative matrix elements do not suffer from power-divergent mixing on the lattice, which significantly complicates calculations of quantities such as the moments of parton distribution functions, provided the smearing scale is kept fixed in the continuum limit. The presence of this smearing scale complicates the connection to the Wilson coefficients of the standard …
Measurement Of Parity-Violating Asymmetry In Electron-Deuteron Inelastic Scattering, D. Wang, (...), D. S. Armstrong, Et Al.
Measurement Of Parity-Violating Asymmetry In Electron-Deuteron Inelastic Scattering, D. Wang, (...), D. S. Armstrong, Et Al.
Arts & Sciences Articles
The parity-violating asymmetries between a longitudinally polarized electron beam and an unpolarized deuterium target have been measured recently. The measurement covered two kinematic points in the deep-inelastic scattering region and five in the nucleon resonance region. We provide here details of the experimental setup, data analysis, and results on all asymmetry measurements including parity-violating electron asymmetries and those of inclusive pion production and beam-normal asymmetries. The parity-violating deep-inelastic asymmetries were used to extract the electron-quark weak effective couplings, and the resonance asymmetries provided the first evidence for quark-hadron duality in electroweak observables. These electron asymmetries and their interpretation were published …