Axial Anomaly, Dirac Sea, and the Chiral Magnetic Effect (open access)

Axial Anomaly, Dirac Sea, and the Chiral Magnetic Effect

Gribov viewed the axial anomaly as a manifestation of the collective motion of Dirac fermions with arbitrarily high momenta in the vacuum. In the presence of an external magnetic field and a chirality imbalance, this collective motion becomes directly observable in the form of the electric current - this is the chiral magnetic effect (CME). I give an elementary introduction into the physics of CME, and discuss the experimental status and recent developments.
Date: May 26, 2010
Creator: Kharzeev, D.E.
Object Type: Article
System: The UNT Digital Library
Data Reduction Processes Using FPGA for MicroBooNE Liquid Argon Time Projection Chamber (open access)

Data Reduction Processes Using FPGA for MicroBooNE Liquid Argon Time Projection Chamber

MicroBooNE is a liquid Argon time projection chamber to be built at Fermilab for an accelerator-based neutrino physics experiment and as part of the R&D strategy for a large liquid argon detector at DUSEL. The waveforms of the {approx}9000 sense wires in the chamber are continuously digitized at 2 M samples/s - which results in a large volume of data coming off the TPC. We have developed a lossless data reduction scheme based on Huffman Coding and have tested the scheme on cosmic ray data taken from a small liquid Argon time projection chamber, the BO detector. For sense wire waveforms produced by cosmic ray tracks, the Huffman Coding scheme compresses the data by a factor of approximately 10. The compressed data can be fully recovered back to the original data since the compression is lossless. In addition to accelerator neutrino data, which comes with small duty cycle in sync with the accelerator beam spill, continuous digitized waveforms are to be temporarily stored in the MicroBooNE data-acquisition system for about an hour, long enough for an external alert from possible supernova events. Another scheme, Dynamic Decimation, has been developed to compress further the potential supernova data so that the storage …
Date: May 26, 2010
Creator: Wu, Jinyuan
Object Type: Article
System: The UNT Digital Library
Fermi surface of SrFe2P2 determined by de Haas-van Alphen effect (open access)

Fermi surface of SrFe2P2 determined by de Haas-van Alphen effect

We report measurements of the Fermi surface (FS) of the ternary iron-phosphide SrFe{sub 2}P{sub 2} using the de Haas-van Alphen effect. The calculated FS of this compound is very similar to SrFe{sub 2}As{sub 2}, the parent compound of the high temperature superconductors. Our data show that the Fermi surface is composed of two electron and two hole sheets in agreement with bandstructure calculations. Several of the sheets show strong c-axis warping emphasizing the importance of three-dimensionality in the non-magnetic state of the ternary pnictides. We find that the electron and hole pockets have a different topology, implying that this material does not satisfy a ({pi},{pi}) nesting condition.
Date: May 26, 2010
Creator: Analytis, J.G.
Object Type: Article
System: The UNT Digital Library
Gluon Evolution and Saturation Proceedings (open access)

Gluon Evolution and Saturation Proceedings

Almost 40 years ago, Gribov and colleagues at the Leningrad Nuclear Physics Institute developed the ideas that led to the Dokhsitzer-Gribov-Altarelli-Parisi the Baltisky-Fadin-Kuraev-Lipatov equations. These equations describe the evolution of the distributions for quarks and gluon inside a hadron to increased resolution scale of a probe or to smaller values of the fractional momentum of a hadronic constituent. I motivate and discuss the generalization required of these equations needed for high energy processes when the density of constituents is large. This leads to a theory of saturation realized by the Color Glass Condensate
Date: May 26, 2010
Creator: McLerran, L. D.
Object Type: Article
System: The UNT Digital Library
INDEPENDENT VERIFICATION REVIEW AND SURVEY of the Argonne National Laboratory Building 301 Footprint (open access)

INDEPENDENT VERIFICATION REVIEW AND SURVEY of the Argonne National Laboratory Building 301 Footprint

INDEPENDENT VERIFICATION REVIEW AND SURVEY of the Argonne National Laboratory Building 301 Footprint, Argonne Illinois 5061-SR-01-0
Date: May 26, 2010
Creator: Bailey, E.N.
Object Type: Report
System: The UNT Digital Library
Light-Front Quantization Approach to the Gauge Gravity Correspondence and Hadron Spectroscopy (open access)

Light-Front Quantization Approach to the Gauge Gravity Correspondence and Hadron Spectroscopy

We find a correspondence between semiclassical QCD quantized on the light-front and a dual gravity model in anti-de Sitter (AdS) space, thus providing an initial approximation to QCD in its strongly coupled regime. This correspondence - light-front holography - leads to a light-front Hamiltonian and relativistic bound-state wave equations that are functions of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within hadrons at equal lightfront time. The eigenvalues of the resulting light-front Schrodinger and Dirac equations are consistent with the observed light meson and baryon spectrum, and the eigenmodes provide the light-front wavefunctions, the probability amplitudes describing the dynamics of the hadronic constituents. The light-front equations of motion, which are dual to an effective classical gravity theory, possess remarkable algebraic and integrability properties which are dictated by the underlying conformal properties of the theory. We extend the algebraic construction to include a confining potential while preserving the integrability of the mesonic and baryonic bound-state equations.
Date: May 26, 2010
Creator: de Teramond, Guy F.; U., /Costa Rica & Brodsky, Stanley J.
Object Type: Article
System: The UNT Digital Library
Mechanics of Individual, Isolated Vortices in a Cuprate Superconductor (open access)

Mechanics of Individual, Isolated Vortices in a Cuprate Superconductor

None
Date: May 26, 2010
Creator: Auslaender, O.M.
Object Type: Article
System: The UNT Digital Library
Polar Kerr Effect as Probe for Time-Reversal Symmetry Breaking in Unconventional Superconductors (open access)

Polar Kerr Effect as Probe for Time-Reversal Symmetry Breaking in Unconventional Superconductors

The search for broken time reversal symmetry (TRSB) in unconventional superconductors intensified in the past year as more systems have been predicted to possess such a state. Following our pioneering study of TRSB states in Sr{sub 2}RuO{sub 4} using magneto-optic probes, we embarked on a systematic study of several other of these candidate systems. The primary instrument for our studies is the Sagnac magneto-optic interferometer, which we recently developed. This instrument can measure magneto-optic Faraday or Kerr effects with an unprecedented sensitivity of 10 nanoradians at temperatures as low as 100 mK. In this paper we review our recent studies of TRSB in several systems, emphasizing the study of the pseudogap state of high temperature superconductors and the inverse proximity effect in superconductor/ferromagnet proximity structures.
Date: May 26, 2010
Creator: Kapitulnik, A.
Object Type: Article
System: The UNT Digital Library
Quantum Oscillation Studies of the Fermi Surface of LaFePO (open access)

Quantum Oscillation Studies of the Fermi Surface of LaFePO

We review recent experimental measurements of the Fermi surface of the iron-pnictide superconductor LaFePO using quantum oscillation techniques. These studies show that the Fermi surface topology is close to that predicted by first principles density functional theory calculations, consisting of quasi-twodimensional electron-like and hole-like sheets. The total volume of the two hole sheets is almost equal to that of the two electron sheets, and the hole and electron Fermi surface sheets are close to a nesting condition. No evidence for the predicted three dimensional pocket arising from the Fe d{sub z}{sup 2} band is found. Measurements of the effective mass suggest a renormalisation of around two, close to the value for the overall band renormalisation found in recent angle resolved photoemission measurements.
Date: May 26, 2010
Creator: Carrington, A.
Object Type: Article
System: The UNT Digital Library
Quantum Oscillations in the Parent pnictide BaFe2As2 : Itinerant Electrons in the Reconstructed State (open access)

Quantum Oscillations in the Parent pnictide BaFe2As2 : Itinerant Electrons in the Reconstructed State

We report quantum oscillation measurements that enable the direct observation of the Fermi surface of the low temperature ground state of BaFe{sub 2}As{sub 2}. From these measurements we characterize the low energy excitations, revealing that the Fermi surface is reconstructed in the antiferromagnetic state, but leaving itinerant electrons in its wake. The present measurements are consistent with a conventional band folding picture of the antiferromagnetic ground state, placing important limits on the topology and size of the Fermi surface.
Date: May 26, 2010
Creator: Analytis, J.G.
Object Type: Article
System: The UNT Digital Library
RegPredict: an integrated system for regulon inference in prokaryotes by comparative genomics approach (open access)

RegPredict: an integrated system for regulon inference in prokaryotes by comparative genomics approach

RegPredict web server is designed to provide comparative genomics tools for reconstruction and analysis of microbial regulons using comparative genomics approach. The server allows the user to rapidly generate reference sets of regulons and regulatory motif profiles in a group of prokaryotic genomes. The new concept of a cluster of co-regulated orthologous operons allows the user to distribute the analysis of large regulons and to perform the comparative analysis of multiple clusters independently. Two major workflows currently implemented in RegPredict are: (i) regulon reconstruction for a known regulatory motif and (ii) ab initio inference of a novel regulon using several scenarios for the generation of starting gene sets. RegPredict provides a comprehensive collection of manually curated positional weight matrices of regulatory motifs. It is based on genomic sequences, ortholog and operon predictions from the MicrobesOnline. An interactive web interface of RegPredict integrates and presents diverse genomic and functional information about the candidate regulon members from several web resources. RegPredict is freely accessible at http://regpredict.lbl.gov.
Date: May 26, 2010
Creator: Novichkov, Pavel S.; Rodionov, Dmitry A.; Stavrovskaya, Elena D.; Novichkova, Elena S.; Kazakov, Alexey E.; Gelfand, Mikhail S. et al.
Object Type: Article
System: The UNT Digital Library
Search for lepton flavor violating decay τ<sup>-</sup> →ℓ<sup>-</sup>ℓ<sup>+</sup>ℓ<sup>-</sup>ℓ = e, μ at BaBar (open access)

Search for lepton flavor violating decay τ<sup>-</sup> →ℓ<sup>-</sup>ℓ<sup>+</sup>ℓ<sup>-</sup>ℓ = e, μ at BaBar

The Standard Model (SM) is one of the most tested and verified physical theories of all time, present experimental observations are consistent with SM expectations. On the other hand SM can not explain many physical observations: the cosmological observations possibly infer the presence of dark matter which is clearly beyond the SM expectations; the SM Higgs model, while explaining the generation of fermion masses, can not explain the hierarchy problem and a non natural fine tuning of SM is needed to cancel out quadratic divergences in the Higgs boson mass. New physics (NP) beyond SM should hence be investigated: rising the energy above NP processes thresholds, and detecting new particles or new effects not predicted by the standard model directly, is one of the possible approaches; another approach is to make precision measurements of well known processes or looking for rare processes which involve higher order contribution from NP processes, this approach need higher luminosities with respect to the previous approach but lower beam energies. Search for Lepton Flavor Violation (LFV) in charged lepton decays is promising: neutrino physics provides indeed a clear and unambiguous evidence of LFV in the neutral lepton sector via mixing processes, which have been observed …
Date: May 26, 2010
Creator: Cervelli, Alberto
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Silicon Detector Letter of Intent (open access)

Silicon Detector Letter of Intent

This document presents the current status of SiD's effort to develop an optimized design for an experiment at the International Linear Collider. It presents detailed discussions of each of SiD's various subsystems, an overview of the full GEANT4 description of SiD, the status of newly developed tracking and calorimeter reconstruction algorithms, studies of subsystem performance based on these tools, results of physics benchmarking analyses, an estimate of the cost of the detector, and an assessment of the detector R&amp;D needed to provide the technical basis for an optimised SiD.
Date: May 26, 2010
Creator: Aihara, H.; Burrows, P. & Oreglia, M.
Object Type: Report
System: The UNT Digital Library
"Snowflake" divertor configuration in NSTX (open access)

"Snowflake" divertor configuration in NSTX

None
Date: May 26, 2010
Creator: Soukhanovskii, V. A.; Ahn, J. W.; Bell, R. E.; Gates, D. A.; Gerhardt, S.; Kaita, R. et al.
Object Type: Article
System: The UNT Digital Library
Surrogate Approaches for Neutron Capture (open access)

Surrogate Approaches for Neutron Capture

None
Date: May 26, 2010
Creator: Escher, J E; Dietrich, F S & Scielzo, N D
Object Type: Article
System: The UNT Digital Library
Topological change of the Fermi surface in ternary iron-pnictides with reduced c/a ratio: A dHvA study of CaFe2P2 (open access)

Topological change of the Fermi surface in ternary iron-pnictides with reduced c/a ratio: A dHvA study of CaFe2P2

We report a de Haas-van Alphen effect study of the Fermi surface of CaFe{sub 2}P{sub 2} using low temperature torque magnetometry up to 45 T. This system is a close structural analogue of the collapsed tetragonal non-magnetic phase of CaFe{sub 2}As{sub 2}. We find the Fermi surface of CaFe{sub 2}P{sub 2} to differ from other related ternary phosphides in that its topology is highly dispersive in the c-axis, being three-dimensional in character and with identical mass enhancement on both electron and hole pockets ({approx} 1.5). The dramatic change in topology of the Fermi surface suggests that in a state with reduced (c/a) ratio, when bonding between pnictogen layers becomes important, the Fermi surface sheets are unlikely to be nested.
Date: May 26, 2010
Creator: Coldea, Amalia I.; Andrew, C. M. J.; U., /Bristol; Analytis, J. G.; /SIMES, Stanford /SLAC /Stanford U., Phys. Dept.; McDonald, R. D. et al.
Object Type: Article
System: The UNT Digital Library
Topological Insulators and Nematic Phases from Spontaneous Symmetry Breaking in (open access)

Topological Insulators and Nematic Phases from Spontaneous Symmetry Breaking in

We investigate the stability of a quadratic band-crossing point (QBCP) in 2D fermionic systems. At the non-interacting level, we show that a QBCP exists and is topologically stable for a Berry flux {-+}2{pi}, if the point symmetry group has either fourfold or sixfold rotational symmetries. This putative topologically stable free-fermion QBCP is marginally unstable to arbitrarily weak shortrange repulsive interactions. We consider both spinless and spin-1/2 fermions. Four possible ordered states result: a quantum anomalous Hall phase, a quantum spin Hall phase, a nematic phase, and a nematic-spin-nematic phase.
Date: May 26, 2010
Creator: Sun, K.
Object Type: Article
System: The UNT Digital Library
A Twisted Ladder: Relating the Fe Superconductors to the High Tc Cuprates (open access)

A Twisted Ladder: Relating the Fe Superconductors to the High Tc Cuprates

We construct a 2-leg ladder model of an Fe-pnictide superconductor and discuss its properties and relationship with the familiar 2-leg cuprate model. Our results suggest that the underlying pairing mechanism for the Fe-pnictide superconductors is similar to that for the cuprates.
Date: May 26, 2010
Creator: Berg, E.
Object Type: Article
System: The UNT Digital Library
VERIFICATION SURVEY ACTIVITIES IN FS SURVEY UNITS 7, 8, 9, 10, 11, 13 & 14 AT THE SEPARATIONS PROCESS RESEARCH UNIT (open access)

VERIFICATION SURVEY ACTIVITIES IN FS SURVEY UNITS 7, 8, 9, 10, 11, 13 & 14 AT THE SEPARATIONS PROCESS RESEARCH UNIT

FINAL INTERIM REPORT VERIFICATION SURVEY ACTIVITIES IN FINAL STATUS SURVEY UNITS 7, 8, 9, 10, 11, 13 AND 14 AT THE SEPARATIONS PROCESS RESEARCH UNIT, Niskayuna, New York 0496-SR-03-0. The Separations Process Research Unit (SPRU) facilities were constructed in the late 1940s to research the chemical separation of plutonium and uranium. SPRU operated between February 1950 and October 1953. The research activities ceased following the successful development of the reduction/oxidation and plutonium/uranium extraction processes that were subsequently used by the Hanford and the Savannah River sites.
Date: May 26, 2010
Creator: JADICK, M.G.
Object Type: Report
System: The UNT Digital Library
Verification with gamma-ray and fast neutron detection (open access)

Verification with gamma-ray and fast neutron detection

None
Date: May 26, 2010
Creator: Wurtz, R. E.; Glenn, A. M.; Kerr, P. L.; Kim, K. S.; Nakae, L. F.; Newby, R. J. et al.
Object Type: Article
System: The UNT Digital Library

Wind Turbine Manufacturers in the United States: Locations and Local Impacts

Suzanne Tegen's presentation about U.S. wind energy manufacturing (presented at WINDPOWER 2010 in Dallas) provides information about challenges to modeling renewables; wind energy's economic "ripple effect"; case studies about wind-related manufacturing in Colorado, Iowa, Ohio, and Indiana; manufacturing maps for the Great Lakes region, Arkansas, and the United States; sample job announcements; and U.S. Treasury Grant 1603 funding.
Date: May 26, 2010
Creator: Tegen, S.
Object Type: Presentation
System: The UNT Digital Library