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Balloon-Borne Gamma-Ray Polarimeter (PoGO) to Study Black Holes, Pulsars, and AGN Jets: Design and Calibration(SULI)

Description: Polarization measurements at X-ray and gamma-ray energies can provide crucial information on the emission region around massive compact objects such as black holes and neutron stars. The Polarized Gamma-ray Observer (PoGO) is a new balloon-borne instrument designed to measure polarization from such astrophysical objects in the 30-100 keV range, under development by an international collaboration with members from United States, Japan, Sweden and France. The PoGO instrument has been designed by … more
Date: December 15, 2005
Creator: Apte, Zachary & /SLAC, /Hampshire Coll.
Partner: UNT Libraries Government Documents Department
open access

Analysis of B -> omega lv Decays with BaBar (SULI)

Description: As part of the BaBar project at SLAC to study the properties of B mesons, we have carried out a study of the exclusive charmless semileptonic decay mode B {yields} wlv, which can be used to determine the Cabbibo-Kobayashi-Maskawa matrix element V{sub ub}. Using simulated event samples, this study focuses on determining criteria on variables for selection of B {yields} wlv signal and suppression of background from other types of B{bar B} events and continuum processes. In addition, we determine … more
Date: December 15, 2005
Creator: Chu, Yi-Wen; /MIT; Littlejohn, B.; /Unlisted; Dingfelder, J. & /SLAC
Partner: UNT Libraries Government Documents Department
open access

Reheating Metastable O'Raifeartaigh Models

Description: In theories with multiple vacua, reheating to a temperature greater than the height of a barrier can stimulate transitions from a desirable metastable vacuum to a lower energy state. We discuss the constraints this places on various theories and demonstrate that in a class of supersymmetric models this transition does not occur even for arbitrarily high reheating temperature.
Date: December 13, 2006
Creator: Craig, Nathaniel J.; /SLAC /Stanford U., ITP; Fox, Patrick J.; /LBL, Berkeley; Wacker, Jay G. & /SLAC /Stanford U., ITP
Partner: UNT Libraries Government Documents Department
open access

SCET Sum Rules for B to P and B to V Transition Form Factors

Description: We investigate sum rules for heavy-to-light transition form factors at large recoil derived from correlation functions with interpolating currents for light pseudoscalar or vector fields in soft-collinear effective theory (SCET). We consider both, factorizable and nonfactorizable contributions at leading power in the {Lambda}/m{sub b} expansion and to first order in the strong coupling constant {alpha}{sub s}, neglecting contributions from 3-particle distribution amplitudes in the B-meson. We p… more
Date: December 18, 2007
Creator: De Fazio, Fulvia; /INFN, Bari; Feldmann, Thorsten; U., /Siegen; Hurth, Tobias & /SLAC, /CERN
Partner: UNT Libraries Government Documents Department
open access

An Automated Method for Characterizing the Relaxedness of Galaxy Clusters

Description: Relaxed galaxy clusters are useful tools for probing cosmological parameters like the gas mass fraction of the universe. Selecting relaxed clusters for this purpose can be a time-consuming and subjective task, so we present methods to automate parts of the process. We fit elliptical isophotes to a diverse sample of Chandra cluster data and summarize other methods for quantifying relaxedness which will be included in future work. Analysis of the results of tests from isophote fitting, combined w… more
Date: December 15, 2005
Creator: George, Matt & /SLAC, /Harvard Coll. Observ.
Partner: UNT Libraries Government Documents Department
open access

A Simple Harmonic Universe

Description: We explore simple but novel bouncing solutions of general relativity that avoid singularities. These solutions require curvature k = +1, and are supported by a negative cosmological term and matter with -1 < w < -1 = 3. In the case of moderate bounces (where the ratio of the maximal scale factor a{sub +} to the minimal scale factor a{sub -} is {Omicron}(1)), the solutions are shown to be classically stable and cycle through an infinite set of bounces. For more extreme cases with large a{s… more
Date: December 14, 2011
Creator: Graham, Peter W.; /Stanford U., ITP; Horn, Bart; Kachru, Shamit; /Stanford U., ITP /SLAC; Rajendran, Surjeet et al.
Partner: UNT Libraries Government Documents Department
open access

Scanning Hall Probe Microscopy of Magnetic Vortices inVery Underdoped yttrium-barium-copper-oxide

Description: Since their discovery by Bednorz and Mueller (1986), high-temperature cuprate superconductors have been the subject of intense experimental research and theoretical work. Despite this large-scale effort, agreement on the mechanism of high-T{sub c} has not been reached. Many theories make their strongest predictions for underdoped superconductors with very low superfluid density n{sub s}/m*. For this dissertation I implemented a scanning Hall probe microscope and used it to study magnetic vortic… more
Date: December 2, 2005
Creator: Guikema, Janice Wynn & /SLAC, SSRL
Partner: UNT Libraries Government Documents Department
open access

Investigating the Infrared Properties of Candidate Blazars

Description: Blazars are active galaxies with super-massive black holes, containing jets that accelerate plasma material and produce radiation. They are unique among other active galaxies for properties such as rapid variability and the lack of emission lines. The double-peaked spectral energy distribution (SED) found for most blazar objects suggests that synchrotron radiation and Compton scattering occurs in the jets. This study is an investigation of the infrared (IR) spectra of a selected population of b… more
Date: December 15, 2005
Creator: Hall, Jessica & /SLAC, /Southern California U.
Partner: UNT Libraries Government Documents Department
open access

Dynamic SU(2) structure from seven-branes

Description: We obtain a family of supersymmetric solutions of type IIB supergravity with dynamic SU(2) structure, which describe the local geometry near a stack of four D7-branes and one O7-plane wrapping a rigid four-cycle. The deformation to a generalized complex geometry is interpreted as a consequence of nonperturbative effects in the seven-brane gauge theory. We formulate the problem for seven-branes wrapping the base of an appropriate del Pezzo cone, and in the near-stack limit in which the four-cycl… more
Date: December 16, 2010
Creator: Heidenreich, Ben; McAllister, Liam; /Cornell U., Phys. Dept.; Torroba, Gonzalo & /SLAC /Stanford U., Phys. Dept.
Partner: UNT Libraries Government Documents Department
open access

Monitoring SLAC High Performance UNIX Computing Systems

Description: Knowledge of the effectiveness and efficiency of computers is important when working with high performance systems. The monitoring of such systems is advantageous in order to foresee possible misfortunes or system failures. Ganglia is a software system designed for high performance computing systems to retrieve specific monitoring information. An alternative storage facility for Ganglia's collected data is needed since its default storage system, the round-robin database (RRD), struggles with d… more
Date: December 15, 2005
Creator: Lettsome, Annette K. & /SLAC, /Bethune-Cookman Coll.
Partner: UNT Libraries Government Documents Department
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