Light-Front Holography and Hadronization at the Amplitude Level (open access)

Light-Front Holography and Hadronization at the Amplitude Level

The correspondence between theories in anti-de Sitter space and conformal field theories in physical space-time leads to an analytic, semiclassical model for strongly-coupled QCD which has scale invariance at short distances and color confinement at large distances. Light-front holography is a remarkable feature of AdS/CFT: it allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons at the amplitude level. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates and the behavior of the QCD coupling in the infrared. We suggest that the spatial support of QCD condensates is restricted to the interior of hadrons, since they arise due to the interactions of confined quarks and gluons. Chiral symmetry is thus broken in a limited domain of size 1=m{sub {pi}} in analogy to the limited physical extent of superconductor phases. A new method for computing the hadronization of quark and gluon jets at the amplitude level, an event amplitude generator, is outlined.
Date: July 25, 2008
Creator: Brodsky, Stanley J.; de Teramond, Guy & Shrock, Robert
System: The UNT Digital Library
Neutron Soft Errors in Xilinx FPGAs at Lawrence Berkeley National Laboratory (open access)

Neutron Soft Errors in Xilinx FPGAs at Lawrence Berkeley National Laboratory

The LBNL 88-Inch Cyclotron offers broad-spectrum neutrons for single event effects testing. We discuss results from this beamline for neutron soft upsets in Xilinx Virtex-4 and -5 field-programmable-gate-array (FPGA) devices.
Date: July 25, 2008
Creator: George, Jeffrey S.; Koga, Rocky & McMahan, Margaret A.
System: The UNT Digital Library
Executive Summary of the Workshop on Polarization and Beam Energy Measurements at the ILC (open access)

Executive Summary of the Workshop on Polarization and Beam Energy Measurements at the ILC

This note summarizes the results of the 'Workshop on Polarization and Beam Energy Measurements at the ILC', held at DESY (Zeuthen) April 9-11 2008. The topics for the workshop included (1) physics requirements, (2) polarized sources and low energy polarimetry, (3) BDS polarimeters, (4) BDS energy spectrometers, and (5) physics-based measurements of beam polarization and beam energy from collider data. Discussions focused on the current ILC baseline program as described in the Reference Design Report (RDR), which includes physics runs at beam energies between 100 and 250 GeV, as well as calibration runs on the Z-pole. Electron polarization of P{sub e{sup -}} {approx}> 80% and positron polarization of P{sub e{sup +}} {approx}> 30% are part of the baseline configuration of the machine. Energy and polarization measurements for ILC options beyond the baseline, including Z-pole running and the 1 TeV energy upgrade, were also discussed.
Date: July 25, 2008
Creator: Aurand, B.; Bailey, I.; Bartels, C.; Blair, G.; Brachmann, A.; Clarke, J. et al.
System: The UNT Digital Library
Study of the Decay Ds+ to K+K-e+nu (open access)

Study of the Decay Ds+ to K+K-e+nu

Using 214 fb{sup -1} of data recorded by the BABAR detector at the PEPII electron-positron collider, they study the decay D{sub s}{sup +} {yields} K{sup +}K{sup -}e{sup +}{nu}{sub e}. Except for a small S-wave contribution, the events with K{sup +}K{sup -} masses in the range 1.01-1.03 GeV/c{sup 2} correspond to {phi} mesons. For D{sub s}{sup +} {yields} {phi}e{sup +}{nu}{sub e} decays, they measure the relative normalization of the Lorentz invariant form factors at q{sup 2} = 0, r{sub V} = V(0)/A{sub 1}(0) = 1.849 {+-} 0.060 {+-} 0.095, r{sub 2} = A{sub 2}(0)/A{sub 1}(0) = 0.763 {+-} 0.071 {+-} 0.065 and the pole mass of the axial-vector form factors m{sub A} = (2.28{sub -0.18}{sup +0.23} {+-} 0.18) GeV/c{sup 2}. Within the same K{sup +}K{sup -} mass range, they also measure the relative branching fractions {Beta}(D{sub s}{sup +} {yields} K{sup +}K{sup -}e{sup +}{nu}{sub e})/{Beta}(D{sub s}{sup +} {yields} K{sup +}K{sup -}{pi}{sup +}) - 0.558 {+-} 0.007 {+-} 0.016, from which they obtain the total branching fraction {Beta}(D{sub s}{sup +} {yields} {phi}e{sup +}{nu}{sub e}) = (2.61 {+-} 0.03 {+-} 0.08 {+-} 0.15) x 10{sup -2}. By comparing this value with the predicted decay rate, they extract A{sub 1}(0) = 0.607 {+-} 0.011 {+-} …
Date: July 25, 2008
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E. et al.
System: The UNT Digital Library
A Flight Simulator for ATF2 - A Mechanism for International Collaboration in the Writing and Deployment of Online Beam Dynamics Algorithms (open access)

A Flight Simulator for ATF2 - A Mechanism for International Collaboration in the Writing and Deployment of Online Beam Dynamics Algorithms

The goals of ATF2 are to test a novel compact final focus optics design with local chromaticity correction intended for use in future linear colliders. The newly designed extraction line and final focus system will be used to produce a 37nm vertical waist from an extracted beam from the ATF ring of {approx}30nm vertical normalized emittance, and to stabilize it at the IP-waist to the {approx}2nm level. Static and dynamic tolerances on all accelerator components are very tight; the achievement of the ATF2 goals is reliant on the application of multiple high-level beam dynamics control algorithms to align and tune the electron beam in the extraction line and final focus system. Much algorithmic development work has been done in Japan and by colleagues in collaborating nations in North America and Europe. We describe here development work towards realizing a 'flight simulator' environment for the shared development and implementation of beam dynamics code. This software exists as a 'middle-layer' between the lower-level control systems (EPICS and V-SYSTEM) and the multiple higher-level beam dynamics modeling tools in use by the three regions (SAD, Lucretia, PLACET, MAD...).
Date: July 25, 2008
Creator: White, Glen; Molloy, Stephen; Seryi, Andrei; Schulte, Daniel; Tomas, Rogelio; Kuroda, Shigeru et al.
System: The UNT Digital Library
Standard Practice for Dosimetry of Proton Beams for use in Radiation Effects Testing of Electronics (open access)

Standard Practice for Dosimetry of Proton Beams for use in Radiation Effects Testing of Electronics

Representatives of facilities that routinely deliver protons for radiation effect testing are collaborating to establish a set of standard best practices for proton dosimetry. These best practices will be submitted to the ASTM International for adoption.
Date: July 25, 2008
Creator: McMahan, Margaret A.; Blackmore, Ewart; Cascio, Ethan W.; Castaneda, Carlos; von Przewoski, Barbara & Eisen, Harvey
System: The UNT Digital Library
A High-resolution TOF Detector - A Possible Way to Compete with a RICH Detector (open access)

A High-resolution TOF Detector - A Possible Way to Compete with a RICH Detector

Using two identical 64-pixel Burle/Photonis MCP-PMTs to provide start and stop signals, they have achieved a timing resolution of {sigma}{sub Single{_}detector} {approx} 7.2 ps for N{sub pe} {approx} 50 photoelectrons (N{sub pe}) with a laser diode providing a 1 mm spot on the MCP window. The limiting resolution achieved was {sigma}{sub Single{_}detector} {approx} 5.0 ps for N{sub pe} {approx} 180, for which they estimate the MCP-PMT contribution of {sigma}{sub MCP-PMT} {approx} 4.5 ps. The electronics contribution is estimated as {sigma}{sub Electrons} = 3.42 ps. These results suggest that an ultra-high resolution TOF detector may become a reality at future experiments one day.
Date: July 25, 2008
Creator: Va'vra, J; Ertley, C.; Leith, D. W. G. S.; Ratcliff, B. & Schwiening, J.
System: The UNT Digital Library
PEP-II Status (open access)

PEP-II Status

PEP-II and BaBar have just finished run 7, the last run of the SLAC B-factory. PEP-II was one of the few high-current e+e- colliding accelerators and holds the present world record for stored electrons and stored positrons. It has stored 2.07 A of electrons, nearly 3 times the design current of 0.75 A and it has stored 3.21 A of positrons, 1.5 times more than the design current of 2.14 A. High-current beams require careful design of several systems. The feedback systems that control instabilities, the RF system stability loops, and especially the vacuum systems have to handle the higher power demands. We present here some of the accomplishments of the PEP-II accelerator and some of the problems we encountered while running high-current beams.
Date: July 25, 2008
Creator: Sullivan, M.; Bertsche, K.; Browne, M.; Cai, Y.; Cheng, W.; Colocho, W. et al.
System: The UNT Digital Library
SLIM--An Early Work Revisited (open access)

SLIM--An Early Work Revisited

An early, but at the time illuminating, piece of work on how to deal with a general, linearly coupled accelerator lattice is revisited. This work is based on the SLIM formalism developed in 1979-1981.
Date: July 25, 2008
Creator: Chao, Alex
System: The UNT Digital Library
Novel QCD Phenomena at Electron-Proton Colliders (open access)

Novel QCD Phenomena at Electron-Proton Colliders

I discuss several novel phenomenological features of QCD which are observable in deep inelastic lepton-nucleon and lepton-nucleus scattering. Initial- and final-state interactions from gluon exchange, normally neglected in the parton model, have a profound effect on QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, the diffractive contribution to deep inelastic scattering, and the breakdown of the pQCD Lam-Tung relation in Drell-Yan reactions. Leading-twist diffractive processes in turn lead to nuclear shadowing and non-universal antishadowing--physics not incorporated in the light-front wavefunctions of the nucleus computed in isolation.
Date: July 25, 2008
Creator: Brodsky, Stanley J. & /SLAC /Durham U., IPPP
System: The UNT Digital Library
Study of Hadronic Transitions Between \Upsilon States and Observation of \Upsilon(4S) to\eta\Upsilon(1S) Decay (open access)

Study of Hadronic Transitions Between \Upsilon States and Observation of \Upsilon(4S) to\eta\Upsilon(1S) Decay

The authors present a study of hadronic transitions between {Upsilon}(mS) (m = 4,3,2) and {Upsilon}(nS) (n = 2,1) resonances based on 347.5 fb{sup -1} of data taken with the BABAR detector at the PEP-II storage rings.
Date: July 25, 2008
Creator: Aubert, B.
System: The UNT Digital Library
Beam-Based Alignment, Tuning and Beam Dynamics Studies for the ATF2 Extraction Line and Final Focus System (open access)

Beam-Based Alignment, Tuning and Beam Dynamics Studies for the ATF2 Extraction Line and Final Focus System

Using a new extraction line currently under construction, the ATF2 experiment plans to test the novel compact final focus optics design with local chromaticity correction intended for use in future linear colliders. With a 1.3 GeV design beam of 30nm normalized vertical emittance extracted from the ATF damping ring, the primary goal is to achieve a vertical spot-size at the IP waist of 37nm. We discuss our planned strategy for tuning the ATF2 beam to meet the primary goal. Simulation studies have been performed to asses the effectiveness of the strategy, including 'static' (installation) errors and dynamical effects (ground-motion, mechanical vibration, ring extraction jitter etc.). We have simulated all steps in the tuning procedure, from initial orbit establishment to final IP spot-size tuning. Through a Monte Carlo study of 100's of simulation seeds we find we can achieve a spot-size within {approx}10% of the design optics value in at least 75% of cases. We also ran a simulation to study the long-term performance with the use of beam-based feedbacks.
Date: July 25, 2008
Creator: White, Glen R.; /LAL, Orsay /SLAC; Molloy, S.; Woodley, M. & /SLAC
System: The UNT Digital Library
An Improved Design for a Super-B Interaction Region (open access)

An Improved Design for a Super-B Interaction Region

We present an improved design for a Super-B interaction region. The new design attempts to minimize the bending of the two colliding beams which results from shared magnetic elements near the Interaction Point (IP). The total crossing angle at the IP is increased from 34 mrad to 50 mrad and the distance from the IP to the first quadrupole is increased. Although the two beams still travel through this shared magnet, these changes allow for a new magnetic field design with a septum which gives the magnet two magnetic centers. This greatly reduces the beam bending from this shared quadrupole and thereby reduces the radiative bhabha background for the detector as well as any beam emittance growth from the bending. We describe the new design for the interaction region.
Date: July 25, 2008
Creator: Sullivan, M. K.; Seeman, J.; Wienands, U.; Bettoni, S.; Biagini, M. E.; Raimondi, P. et al.
System: The UNT Digital Library
Sunyaev-Zel'Dovich effect observations of the bullet cluster (1E 0657-56) with APEX-SZ (open access)

Sunyaev-Zel'Dovich effect observations of the bullet cluster (1E 0657-56) with APEX-SZ

We present observations of the Sunyaev-Zel'dovich effect (SZE) in the Bullet cluster (1E 0657-56) using the APEX-SZ instrument at 150 GHz with a resolution of 1'. The main results are maps of the SZE in this massive, merging galaxy cluster. The cluster is detected with 23 sigma significance within the central 1' radius of the source position. The SZE map has a broadly similar morphology to that in existing X-ray maps of this system, and we find no evidence for significant contamination of the SZE emission by radio or IR sources. In order to make simple quantitative comparisons with cluster gas models derived from X-ray observations, we fit our data to an isothermal elliptical beta model, despite the inadequacy of such a model for this complex merging system. With an X-ray derived prior on the power-law index, beta = 1.04+0.16-0.10, we find a core radius rc = 142" +- 18", an axial ratio of 0.889 +- 0.072, and a central temperature decrement of -771 +- 71 muKCMB, including a +-5.5percent flux calibration uncertainty. Combining the APEX-SZ map with a map of projected electron surface density from Chandra X-ray observations, we determine the mass-weighted temperature of the cluster gas to be …
Date: July 25, 2008
Creator: Halverson, N. W.; Lanting, T.; Ade, P. A. R.; Basu, K.; Bender, A. N.; Benson, B. A. et al.
System: The UNT Digital Library
Evidence for Charged B Meson Decays toa_1+/-(1260)pi0 and a_10(1260)pi+/- (open access)

Evidence for Charged B Meson Decays toa_1+/-(1260)pi0 and a_10(1260)pi+/-

None
Date: July 25, 2008
Creator: Aubert, B.; Bona, M.; Boutigny, D.; Karyotakis, Y.; Lees, J. P.; Poireau, V. et al.
System: The UNT Digital Library