Effects of Energy Chirp on Echo-Enabled Harmonic Generation Free-Electron Lasers (open access)

Effects of Energy Chirp on Echo-Enabled Harmonic Generation Free-Electron Lasers

We study effects of energy chirp on echo-enabled harmonic generation (EEHG). Analytical expressions are compared with numerical simulations for both harmonic and bunching factors. We also discuss the EEHG free-electron laser bandwidth increase due to an energy-modulated beam and its pulse length dependence on the electron energy chirp.
Date: February 23, 2009
Creator: Huang, Z.; Ratner, D.; Stupakov, G. & Xiang, D.
Object Type: Report
System: The UNT Digital Library
Precise Predictions for W + 3 Jet Production at Hadron Colliders (open access)

Precise Predictions for W + 3 Jet Production at Hadron Colliders

We report on the first next-to-leading order QCD computation of W + 3-jet production in hadronic collisions including all partonic subprocesses. We compare the results with CDF data from the Tevatron, and find excellent agreement. The renormalization and factorization scale dependence is reduced substantially compared to leading-order calculations. The required one-loop matrix elements are computed using on-shell methods, implemented in a numerical program, BlackHat. We use the SHERPA package to generate the real-emission contributions and to integrate the various contributions over phase space. We use a leading-color (large-N{sub c}) approximation for the virtual part, which we confirm in W + 1,2-jet production to be valid to within three percent. The present calculation demonstrates the utility of on-shell methods for computing next-to-leading-order corrections to processes important to physics analyses at the Large Hadron Collider.
Date: February 23, 2009
Creator: Berger, C.F.; /MIT, LNS; Bern, Z.; /UCLA; Dixon, L.J.; /SLAC et al.
Object Type: Article
System: The UNT Digital Library
Dalitz Plot Analysis of B+- --> pi+-pi+-pi-+ Decays (open access)

Dalitz Plot Analysis of B+- --> pi+-pi+-pi-+ Decays

The authors present a Dalitz-plot analysis of charmless B{sup {+-}} decays to the final state {pi}{sup {+-}}{pi}{sup {+-}}{pi}{sup {-+}} using a sample of (465 {+-} 5) x 10{sup 6} B{bar B} pairs collected by the BABAR experiment at {radical}s = 10.58 GeV. They measure the branching fractions {Beta}(B{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup {+-}}{pi}{sup {-+}}) = (15.2 {+-} 0.6 {+-} 1.2 {+-} 0.4) x 10{sup -6}, {Beta}(B{sup {+-}} {yields} {rho}{sup 0}(770){pi}{sup {+-}}) = (8.1 {+-} 0.7 {+-} 1.2{sub -1.1}{sup +0.4}) x 10{sup -6}, {Beta}(B{sup {+-}} {yields} f{sub 2}(1270){pi}{sup {+-}}) = (1.57 {+-} 0.42 {+-} 0.16{sub -0.19}{sup +0.53}) x 10{sup -6}, and {Beta}(B{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup {+-}}{pi}{sup {-+}} nonresonant) = (5.3 {+-} 0.7 {+-} 0.6{sub -0.5}{sup +1.1}) x 10{sup -6}, where the uncertainties are statistical, systematic, and model-dependent, respectively. Measurements of branching fractions for the modes B{sup {+-}} {yields} {rho}{sup 0}(1450){pi}{sup {+-}} and B{sup {+-}} {yields} f{sub 0}(1370){pi}{sup {+-}} are also presented. They observe no significant direct CP asymmetries for the above modes, and there is no evidence for the decays B{sup {+-}} {yields} f{sub 0}(980){pi}{sup {+-}}, B{sup {+-}} {yields} {chi}{sub c0}{pi}{sup {+-}}, or B{sup {+-}} {yields} {chi}{sub c2}{pi}{sup {+-}}.
Date: February 23, 2009
Creator: Collaboration, The BABAR & Aubert, B.
Object Type: Article
System: The UNT Digital Library
Scalable Methods for Electronic Excitations and Optical Responses of Nanstructures: Mathematics to Algorithms to Observables (open access)

Scalable Methods for Electronic Excitations and Optical Responses of Nanstructures: Mathematics to Algorithms to Observables

This multi-investigator project was concerned with the development and application of new methods and computer codes that would allow realistic modeling of nanosystems. Carter's part in this team effort involved two method/algorithm/code development projects during the first 14 months of this grant. Carter's group has been advancing theory and applications of the orbital-free density functional theory (OF-DFT), the only DFT method that exhibits linear scaling for metals. Such a method offers the possibility of simulating large numbers of atoms with quantum mechanics, such that properties of metallic nanostructures (e.g. nanowires of realistic dimensions) could be investigated. In addition, her group has been developing and applying an embedded correlated wavefunction theory for treating localized excited states in condensed matter (including metals). The application of interest here is spin manipulation at the nanoscale, i.e., spintronics, in which local electron excitations interact with the surrounding material. Her embedded correlation method is ideal for studying such problems.
Date: January 23, 2009
Creator: Carter, Emily A.
Object Type: Report
System: The UNT Digital Library
AdS/CFT and Light-Front Holography: A Theory of Strong Interactions (open access)

AdS/CFT and Light-Front Holography: A Theory of Strong Interactions

Recent developments in the theory of strong interactions are discussed in the framework of the AdS/CFT duality between string theories of gravity in a higher dimension Anti-de Sitter space and conformal quantum field theories in physical space-time. This novel theoretical approach, combined with 'light-front holography', leads to new insights into the quark and gluon structure of hadrons and a viable first approximation to quantum chromodynamics, the fundamental theory of the strong and nuclear interactions.
Date: February 23, 2009
Creator: Brodsky, Stanley J. & Teramond, Guy F.de
Object Type: Article
System: The UNT Digital Library
Matter Dependence of the Three-Loop Soft Anomalous Dimension Matrix (open access)

Matter Dependence of the Three-Loop Soft Anomalous Dimension Matrix

The resummation of soft gluon exchange for QCD hard scattering requires a matrix of anomalous dimensions, which has been computed through two loops. The two-loop matrix is proportional to the one-loop matrix. Recently there have been proposals that this proportionality extends to higher loops. One can test such proposals by computing the dependence of this matrix on the matter content in a generic gauge theory. It is shown that for the matter-dependent part the proportionality extends to three loops for arbitrary massless processes.
Date: January 23, 2009
Creator: Dixon, Lance J.
Object Type: Article
System: The UNT Digital Library
Polarized Photocathode R&D for Future Linear Collliders (open access)

Polarized Photocathode R&D for Future Linear Collliders

It is a challenge to generate full charge electrons from the electron sources without compromising polarization for the proposed ILC and CLIC. It is essential to advance polarized photocathodes to meet the requirements. SLAC has worldwide unique dedicated test facilities, Cathode Test System and dc-Gun Test Laboratory, to fully characterize polarized photocathodes. Recent systematic measurements on a strained-well InAlGaAs/AlGaAs cathode at the facilities show that 87% polarization and 0.3% QE are achieved. The QE can be increased to {approx}1.0% with atomic hydrogen cleaning. The surface charge limit at a very low current intensity and the clear dependence of the polarization on the surface charge limit are observed for the first time. On-going programs to develop photocathodes for the ILC and CLIC are briefly introduced.
Date: January 23, 2009
Creator: Zhou, F; Brachmann, A.; Maruyama, T. & Sheppard, J. C.
Object Type: Article
System: The UNT Digital Library
Use of a Radon Stripping Algorithm for Retrospective Assessment of Air Filter Samples (open access)

Use of a Radon Stripping Algorithm for Retrospective Assessment of Air Filter Samples

An evaluation of a large number of air sample filters was undertaken using a commercial alpha and beta spectroscopy system employing a passive implanted planar silicon (PIPS) detector. Samples were only measured after air flow through the filters had ceased. Use of a commercial radon stripping algorithm was implemented to discriminate anthropogenic alpha and beta activity on the filters from the radon progeny. When uncontaminated air filters were evaluated, the results showed that there was a time-dependent bias in both average estimates and measurement dispersion with the relative bias being small compared to the dispersion. By also measuring environmental air sample filters simultaneously with electroplated alpha and beta sources, use of the radon stripping algorithm demonstrated a number of substantial unexpected deviations. Use of the current algorithm is therefore not recommended for assay applications and so use of the PIPS detector should only be utilized for gross counting without appropriate modifications to the curve fitting algorithm. As a screening method, the radon stripping algorithm might be expected to see elevated alpha and beta activities on air sample filters (not due to radon progeny) around the 200 dpm level.
Date: January 23, 2009
Creator: Hayes, Robert
Object Type: Article
System: The UNT Digital Library
81st Texas Legislature, Senate Bill 917, Chapter 132 (open access)

81st Texas Legislature, Senate Bill 917, Chapter 132

Bill introduced by the Texas Senate relating to the definition of charitable trust for purposes of court jurisdiction.
Date: May 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
81st Texas Legislature, Senate Bill 918, Chapter 133 (open access)

81st Texas Legislature, Senate Bill 918, Chapter 133

Bill introduced by the Texas Senate relating to attorney general participation in proceedings involving charitable trusts.
Date: May 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
81st Texas Legislature, Senate Bill 935, Chapter 134 (open access)

81st Texas Legislature, Senate Bill 935, Chapter 134

Bill introduced by the Texas Senate relating to authorizing a judge of a municipal court to conduct a marriage ceremony.
Date: May 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
81st Texas Legislature, Senate Concurrent Resolutions 20 (open access)

81st Texas Legislature, Senate Concurrent Resolutions 20

Concurrent resolution introduced by the Texas Senate and House of Representatives relating to Granting the legislature permission to adjourn for more than three days during the period beginning on Wednesday, February 18, 2009, and ending on Monday, February 23, 2009.
Date: February 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
81st Texas Legislature, Senate Concurrent Resolutions 68 (open access)

81st Texas Legislature, Senate Concurrent Resolutions 68

Concurrent resolution introduced by the Texas Senate and House of Representatives relating to recognizing the Twentieth Century Club in Lubbock on the occasion of its 100th anniversary.
Date: May 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
81st Texas Legislature, Senate Concurrent Resolutions 69 (open access)

81st Texas Legislature, Senate Concurrent Resolutions 69

Concurrent resolution introduced by the Texas Senate and House of Representatives relating to recognizing Ballet Lubbock on the occasion of its 40th anniversary.
Date: May 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
81st Texas Legislature, Senate Concurrent Resolutions 71 (open access)

81st Texas Legislature, Senate Concurrent Resolutions 71

Concurrent resolution introduced by the Texas Senate and House of Representatives relating to in memory of George Harold Whatley, Jr.
Date: May 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
81st Texas Legislature, Senate Bill 470, Chapter 125 (open access)

81st Texas Legislature, Senate Bill 470, Chapter 125

Bill introduced by the Texas Senate relating to an intercollegiate athletics fee at the University of North Texas.
Date: May 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
81st Texas Legislature, Senate Bill 481, Chapter 126 (open access)

81st Texas Legislature, Senate Bill 481, Chapter 126

Bill introduced by the Texas Senate relating to safety regulations for certain contract carriers.
Date: May 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
81st Texas Legislature, Senate Bill 526, Chapter 127 (open access)

81st Texas Legislature, Senate Bill 526, Chapter 127

Bill introduced by the Texas Senate relating to grants for federally qualified health centers.
Date: May 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
81st Texas Legislature, Senate Bill 547, Chapter 128 (open access)

81st Texas Legislature, Senate Bill 547, Chapter 128

Bill introduced by the Texas Senate relating to transition to competition in the Southwestern Electric Power Company service area.
Date: May 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
81st Texas Legislature, Senate Bill 629, Chapter 129 (open access)

81st Texas Legislature, Senate Bill 629, Chapter 129

Bill introduced by the Texas Senate relating to the operation of certain institutions of higher education as general academic teaching institutions and to the statutory limitation imposed on certain university systems to issue revenue bonds to fund facilities at certain institutions of higher education.
Date: May 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
81st Texas Legislature, Senate Bill 820, Chapter 130 (open access)

81st Texas Legislature, Senate Bill 820, Chapter 130

Bill introduced by the Texas Senate relating to the adoption and amendment of model building codes by certain municipalities.
Date: May 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
81st Texas Legislature, Senate Bill 858, Chapter 131 (open access)

81st Texas Legislature, Senate Bill 858, Chapter 131

Bill introduced by the Texas Senate relating to offering the classroom portion of a driver education course through an alternative method of instruction.
Date: May 23, 2009
Creator: Texas. Legislature. Senate.
Object Type: Legislative Document
System: The Portal to Texas History
Texas Attorney General Opinion: GA-0731 (open access)

Texas Attorney General Opinion: GA-0731

Document issued by the Office of the Attorney General of Texas in Austin, Texas, providing an interpretation of Texas law. It provides the opinion of the Texas Attorney General, Greg Abbott, regarding a legal question submitted for clarification; Whether Kerr County Sheriff is required to maintain a room in the jail dedicated to recording the interrogation of a person arrested for driving while intoxicated (RQ-0783-GA)
Date: July 23, 2009
Creator: Texas. Attorney-General's Office.
Object Type: Text
System: The Portal to Texas History
Texas Attorney General Opinion: GA-0732 (open access)

Texas Attorney General Opinion: GA-0732

Document issued by the Office of the Attorney General of Texas in Austin, Texas, providing an interpretation of Texas law. It provides the opinion of the Texas Attorney General, Greg Abbott, regarding a legal question submitted for clarification:Whether the State of Texas may permit unauthorized aliens to receive the benefit of in-state tuition at Texas state college and universities (RQ-0742-GA).
Date: July 23, 2009
Creator: Texas. Attorney-General's Office.
Object Type: Text
System: The Portal to Texas History