Two- and Three-Body Charmless B Decays at BaBar (open access)

Two- and Three-Body Charmless B Decays at BaBar

We report recent measurements of rare charmless B decays performed by BaBar. The results are based on the final BaBar dataset of 424 fb{sup -1} collected at the PEP-II B-factory based at the SLAC National Accelerator Laboratory. The study of rare B decays is a key ingredient to meet two of the main goals of the B-factories: assessing the validity of the Cabibbo-Kobayashi-Maskawa (CKM) picture of CP-violation by precisely measuring the elements of the Unitarity Triangle (UT), and searching for hints of New Physics (NP), or otherwise constraining NP scenarios, in processes which are suppressed in the Standard Model (SM). In loop processes, in particular, NP at some higher energy scale may manifest itself in the low energy effective theory as new couplings, such as those introduced by new very massive virtual particles in the loop. In NP searches hadronic uncertainties can play a major role, expecially for branching fraction measurements. Many theoretical uncertainties cancel in ratios of amplitudes, and most NP probes are therefore of this kind. In the following sections we report recent measurements, performed by the BaBar Collaboration, that are relevant to NP searches in charmless hadronic B decays.
Date: April 5, 2012
Creator: Stracka, Simone
Object Type: Article
System: The UNT Digital Library
Search for a Low-Mass Higgs Boson (A0) at BaBar (open access)

Search for a Low-Mass Higgs Boson (A0) at BaBar

The BABAR Collaboration has performed three searches for a light Higgs boson, A{sup 0}, in radiative Upsilon ({Upsilon}) decays: {Upsilon}(3S) {yields} {gamma}A{sup 0}, A{sup 0} {yields} {tau}{sup +}{tau}{sup -}; {Upsilon}(nS) {yields} {gamma}A{sup 0}, A{sup 0} {yields} {mu}{sup +}{mu}{sup -} (n = 2,3); and {Upsilon}(3S) {yields} {gamma}A{sup 0}, A{sup 0} {yields} invisible. Such a Higgs boson (A{sup 0}) appears in the Next-to-Minimal Supersymmetric extensions of the Standard Model, where a light CP-odd Higgs boson couples strongly to b-quarks. The searches are based on data samples that consist of 122 x 10{sup 6} {Upsilon}(3S) and 99 x 10{sup 6} {Upsilon}(2S) decays, collected by the BABAR detector at the SLAC National Accelerator Laboratory. The searches reveal no evidence for an A{sup 0}, and product of branching fractions upper limits, at 90% C.L., of (1.5-16) x 10{sup -5}, (0.44-44) x 10{sup -6}, and (0.7-31) x 10{sup -6} were obtained for these searches, respectively. Also, we set the upper limits {Beta}({eta}{sub b} {yields} {tau}{sup +}{tau}{sup -}) < 8% and {Beta}({eta}{sub b} {yields} {mu}{sup +}{mu}{sup -}) < 0.9%.
Date: April 5, 2012
Creator: Mokhtar, Arafat Gabareen
Object Type: Article
System: The UNT Digital Library
Observation of Laser Induced Magnetization Dynamics in Co/Pd Multilayers with Coherent X-ray Scattering (open access)

Observation of Laser Induced Magnetization Dynamics in Co/Pd Multilayers with Coherent X-ray Scattering

We report on time-resolved coherent x-ray scattering experiments of laser induced magnetization dynamics in Co/Pd multilayers with a high repetition rate optical pump x-ray probe setup. Starting from a multi-domain ground state, the magnetization is uniformly reduced after excitation by an intense 50 fs laser pulse. Using the normalized time correlation, we study the magnetization recovery on a picosecond timescale. The dynamic scattering intensity is separated into an elastic portion at length scales above 65 nm which retains memory of the initial domain magnetization, and a fluctuating portion at smaller length scales corresponding to domain boundary motion during recovery.
Date: April 5, 2012
Creator: Wu, Benny
Object Type: Article
System: The UNT Digital Library
Discovery of Very High Energy Gamma Rays from PKS 1424+240 and Multiwavelength Constraints on its Redshift (open access)

Discovery of Very High Energy Gamma Rays from PKS 1424+240 and Multiwavelength Constraints on its Redshift

We report the first detection of very-high-energy (VHE) gamma-ray emission above 140GeV from PKS 1424+240, a BL Lac object with an unknown redshift. The photon spectrum above 140GeV measured by VERITAS is well described by a power law with a photon index of 3.8 {+-}0.5{sub stat} {+-} 0.3{sub syst} and a flux normalization at 200 GeV of (5.1 {+-} 0.9{sub stat} {+-} 0.5{sub syst}) x 10{sup -11} TeV{sup -1} cm{sup -2} s{sup -1}, where stat and syst denote the statistical and systematical uncertainty, respectively. The VHE flux is steady over the observation period between MJD 54881 and 55003 (2009 February 19 to June 21). Flux variability is also not observed in contemporaneous high energy observations with the Fermi Large Area Telescope (LAT). Contemporaneous X-ray and optical data were also obtained from the Swift XRT and MDM observatory, respectively. The broadband spectral energy distribution (SED) is well described by a one-zone synchrotron self-Compton (SSC) model favoring a redshift of less than 0.1. Using the photon index measured with Fermi in combination with recent extragalactic background light (EBL) absorption models it can be concluded from the VERITAS data that the redshift of PKS 1424+240 is less than 0.66.
Date: April 5, 2012
Creator: Acciari, V. A.; Aliu, E.; Arlen, T.; Aune, T.; Bautista, M.; Beilicke, M. et al.
Object Type: Report
System: The UNT Digital Library
Expert Unreviewed Safety Question Determinations (USQD) (open access)

Expert Unreviewed Safety Question Determinations (USQD)

None
Date: April 5, 2012
Creator: Mitchell, M A & Montgomery, P
Object Type: Article
System: The UNT Digital Library
Dynamic structure factor in warm dense beryllium (open access)

Dynamic structure factor in warm dense beryllium

None
Date: April 5, 2012
Creator: Glenzer, S H; Fortmann, C; Doeppner, T; Plagemann, K U; Sperling, P; Thiele, R et al.
Object Type: Article
System: The UNT Digital Library
Final Report (open access)

Final Report

The purpose of this project was to better understand the 'Multiscale Dynamics of Relaxor Ferroelectrics'. The output of the project is summarized in the narrative. The results of the work were presented at a number of different conferences and four papers were written, the references to which are also indicated in the report and which have also been uploaded on e-link. The multiscale dynamics of relaxors was clearly identified in the three characteristic temperatures that were identified. In particular, we were the first group to identify an intermediate temperature, T*, at which the correlations between off-center ions in relaxor cross-over from being dynamic to being static and giving rise to the characteristic relaxor behavior in the dielectric constant. Other groups have now confirmed the existence of such an intermediate temperature. We also made and reported two other observations: (1) a coherent interference phenomena (EIT-like effect) near the transition of several relaxors, which provides information on the nature and mechanism of the transition; and (2) in a similar way, inelastic neutron scattering results were interpreted as resonant scattering of acoustic phonons by localized modes in polar nanodomains. In parallel with the neutron scattering work, we also developed a theory of the …
Date: April 5, 2012
Creator: Toulouse, J.
Object Type: Report
System: The UNT Digital Library
Review of the WECC EDT phase 2 EIM benefits analysis and results report. (open access)

Review of the WECC EDT phase 2 EIM benefits analysis and results report.

A region-wide Energy Imbalance Market (EIM) was recently proposed by the Western Electricity Coordinating Council (WECC). In order for the Western Area Power Administration (Western) to make more informed decisions regarding its involvement in the EIM, Western asked Argonne National Laboratory (Argonne) to review the EIM benefits study (the October 2011 revision) performed by Energy and Environmental Economics, Inc. (E3). Key components of the E3 analysis made use of results from a study conducted by the National Renewable Energy Laboratory (NREL); therefore, we also reviewed the NREL work. This report examines E3 and NREL methods and models used in the EIM study. Estimating EIM benefits is very challenging because of the complex nature of the Western Interconnection (WI), the variability and uncertainty of renewable energy resources, and the complex decisions and potentially strategic bidding of market participants. Furthermore, methodologies used for some of the more challenging aspects of the EIM have not yet matured. This review is complimentary of several components of the EIM study. Analysts and modelers clearly took great care when conducting detailed simulations of the WI using well-established industry tools under stringent time and budget constraints. However, it is our opinion that the following aspects of the …
Date: April 5, 2012
Creator: Veselka, T.D.; Poch, L.A. & Botterud, A. (Decision and Information Sciences)
Object Type: Report
System: The UNT Digital Library
Layout And Results From The Initial Opeeration Of The High-resolution X-ray Imaging Crystal Spectrometer On The Large Helical Device (open access)

Layout And Results From The Initial Opeeration Of The High-resolution X-ray Imaging Crystal Spectrometer On The Large Helical Device

First results of ion and electron temperature pro le measurements from the x-ray imaging crystal spectrometer (XICS) diagnostic on the Large Helical Device (LHD) are presented. This diagnostic system has been operational since the beginning of the 2011 LHD experimental campaign and is the rst application of the XICS diagnostic technique to helical plasma geometry. The XICS diagnostic provides measurements of ion and electron temperature pro les in LHD with a spatial resolution of 2cm and a time resolution of ≥#21; 10ms. Ion temperature pro les from the XICS diagnostic are possible under conditions where charge exchange recombination spectroscopy (CXRS) is not possible (high density) or is perturbative to the plasma (low density or radio frequency heated plasmas). Measurements are made by using a spherically bent crystal to provide a spectrally resolved 1D image of the plasma from line integrated emission of helium-like Ar16+. The nal hardware design and con guration are detailed along with the calibration procedures. Line-integrated ion and electron temperature measurements are presented, and the measurement accuracy is discussed. Finally central temperature measurements from the XICS system are compared to measurements from the Thomson scattering and CXRS systems, showing excellent agreement.
Date: April 5, 2012
Creator: Pablant, N A; Delgado-Apricio, L; Goto, M; Hill, K W; Lzerson, S; Morita, S et al.
Object Type: Report
System: The UNT Digital Library
Unitarity Bounds and RG Flows in Time Dependent Quantum Field Theory (open access)

Unitarity Bounds and RG Flows in Time Dependent Quantum Field Theory

We generalize unitarity bounds on operator dimensions in conformal field theory to field theories with spacetime dependent couplings. Below the energy scale of spacetime variation of the couplings, their evolution can strongly affect the physics, effectively shifting the infrared operator scaling and unitarity bounds determined from correlation functions in the theory. We analyze this explicitly for large-N double-trace flows, and connect these to UV complete field theories. One motivating class of examples comes from our previous work on FRW holography, where this effect explains the range of flavors allowed in the dual, time dependent, field theory.
Date: April 5, 2012
Creator: Dong, Xi; Horn, Bart; Silverstein, Eva; Torroba, Gonzalo & /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC
Object Type: Report
System: The UNT Digital Library
Switchgrass Demonstration Project (open access)

Switchgrass Demonstration Project

Develop a pilot study that establishes up to 120 acres of cropland in switchgrass and 20 acres on a TN Experiment Station Farm. This subtask would assess production of switchgrass within the state of Tennessee under a variety of conditions and topography through on-farm production totaling 120 acres. Farms would be selected to participate through a bid process. Costs of establishment and maintenance of the switchgrass would be covered. In addition, allowances would be made for covering land rent and providing a yield incentive. An information and education program would be provided to producers prior to the bid process to assist producers in their bid decision. Agronomic, logistic, energy conversion and farming system issues associated with commercialization of a biomass energy industry are evaluated. Information on the opportunities for producing switchgrass as an energy feedstock are extended
Date: April 5, 2012
Creator: Ugarte, Burton C. English and Daniel De La Torre
Object Type: Report
System: The UNT Digital Library
Conceptual Design - Polar Drive Ignition Campaign (open access)

Conceptual Design - Polar Drive Ignition Campaign

The Laboratory for Laser Energetics (LLE) at the University of Rochester is proposing a collaborative effort with Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratories (LANL), the Naval Research Laboratory (NRL), and General Atomics (GA) with the goal of developing a cryogenic polar drive (PD) ignition platform on the National Ignition Facility (NIF). The scope of this proposed project requires close discourse among theorists, experimentalists, and laser and system engineers. This document describes how this proposed project can be broken into a series of parallel independent activities that, if implemented, could deliver this goal in the 2017 timeframe. This Conceptual Design document is arranged into two sections: mission need and design requirements. Design requirements are divided into four subsystems: (1) A point design that details the necessary target specifications and laser pulse requirements; (2) The beam smoothing subsystem that describes the MultiFM 1D smoothing by spectral dispersion (SSD); (3) New optical elements that include continuous phase plates (CPP's) and distributed polarization rotators (DPR's); and (4) The cryogenic target handling and insertion subsystem, which includes the design, fabrication, testing, and deployment of a dedicated PD ignition target insertion cryostat (PD-ITIC). This document includes appendices covering: the primary criteria and functional …
Date: April 5, 2012
Creator: Hansen, R
Object Type: Report
System: The UNT Digital Library
Muon Muon Collider: Feasibility Study (open access)

Muon Muon Collider: Feasibility Study

A feasibility study is presented of a 2 + 2 TeV muon collider with a luminosity of L = 10{sup 35} cm{sup -2}s{sup -1}. The resulting design is not optimized for performance, and certainly not for cost; however, it does suffice - we believe - to allow us to make a credible case, that a muon collider is a serious possibility for particle physics and, therefore, worthy of R and D support so that the reality of, and interest in, a muon collider can be better assayed. The goal of this support would be to completely assess the physics potential and to evaluate the cost and development of the necessary technology. The muon collider complex consists of components which first produce copious pions, then capture the pions and the resulting muons from their decay; this is followed by an ionization cooling channel to reduce the longitudinal and transverse emittance of the muon beam. The next stage is to accelerate the muons and, finally, inject them into a collider ring wich has a small beta function at the colliding point. This is the first attempt at a point design and it will require further study and optimization. Experimental work will be …
Date: April 5, 2012
Creator: Gallardo, J. C.; Palmer, R. B.; Tollestrup, A. V.; Sessler, A. M.; Skrinsky, A. N.; Geer, S. et al.
Object Type: Article
System: The UNT Digital Library