Measurement of the forward-backward asymmetry in top quark-antiquark production in p(p)over-bar collisions using the lepton plus jets channel
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
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Search for B + → e + ν e and B + → μ + ν μ decays using hadronic tagging
We present a search for the rare leptonic decays B + → e + ν e and B + → μ + ν μ , using the full Υ(4S) data sample of 772 × 10 6 BB¯ pairs collected with the Belle detector at the KEKB asymmetric-energy e + e – collider. One of the B mesons from the Υ(4S) → BB¯ decay is fully reconstructed in a hadronic mode, while the recoiling side is analyzed for the signal decay. Here, we find no evidence of a signal in any of the decay modes. Upper limits of the corresponding branching fractions are determined as B(B + → e + ν e ) < 3.5 × 10 –6 and B(B + → μ + ν μ ) < 2.7 × 10 –6 at 90% confidence level.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of exclusive γ γ → W + W - production and search for exclusive Higgs boson production in p p collisions at s = 8 TeV using the ATLAS detector
Searches for exclusively produced W boson pairs in the process p p ( γ γ ) → p W + W - p and an exclusively produced Higgs boson in the process p p ( g g ) → p H p have been performed using e ± μ ∓ final states. These measurements use 20.2 fb - 1 of p p collisions collected by the ATLAS experiment at a center-of-mass energy √ s = 8 TeV at the LHC. Exclusive production of W + W - consistent with the Standard Model prediction is found with 3.0 σ significance. The exclusive W + W - production cross section is determined to be σ ( γ γ → W + W - → e ± μ ∓ X ) = 6.9 ± 2.2 ( stat ) ± 1.4 ( sys ) fb , in agreement with the Standard Model prediction. Limits on anomalous quartic gauge couplings are set at 95% confidence level as - 1.7 × 10 - 6 < a W 0 / Λ 2 < 1.7 × 10 - 6 GeV - 2 and - 6.4 × 10 - 6 < a W C / Λ 2 < 6.3 × 10 - 6 GeV - 2 . A 95% confidence-level upper limit on the total production cross section for an exclusive Higgs boson is set to 1.2 pb.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of the t t ¯ production cross section in the τ + jets final state in p p collisions at s = 8 TeV using the ATLAS detector
A measurement of the inclusive p p → t $\bar{t}$ + X production cross section in the τ + jets final state using only the hadronic decays of the τ lepton is presented. The measurement is performed using 20.2 fb -1 of proton-proton collision data recorded at a center-of-mass energy of √ s = 8 TeV with the ATLAS detector at the Large Hadron Collider. The cross section is measured via a counting experiment by imposing a set of selection criteria on the identification and kinematic variables of the reconstructed particles and jets, and on event kinematic variables and characteristics. The production cross section is measured to be σ t $\bar{t}$ = 239 ± 29 pb , which is in agreement with the measurements in other final states and the theoretical predictions at this center-of-mass energy.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Combination of searches for heavy resonances decaying into bosonic and leptonic final states using 36 fb - 1 of proton-proton collision data at s = 13 TeV with the ATLAS detector
Searches for new heavy resonances decaying into different pairings of W, Z, or Higgs bosons, as well as directly into leptons, are presented using a data sample corresponding to 36.1 fb -1 of pp collisions at $ \sqrt{s}=13 $ TeV collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Analyses selecting bosonic decay modes in the qqqq, ννqq, ℓνqq, ℓℓqq, ℓνℓν, ℓℓνν, ℓνℓℓ, ℓℓℓℓ, qqbb, ννbb, ℓνbb, and ℓℓbb final states are combined, searching for a narrow-width resonance. Likewise, analyses selecting the leptonic ℓν and ℓℓ final states are also combined. These two sets of analyses are then further combined. No significant deviation from the Standard Model predictions is observed. Three benchmark models are tested: a model predicting the existence of a new heavy scalar singlet, a simplified model predicting a heavy vector-boson triplet, and a bulk Randall-Sundrum model with a heavy spin-2 Kaluza-Klein excitation of the graviton. Cross section limits are set at the 95% confidence level using an asymptotic approximation and are compared with predictions for the benchmark models. These limits are also expressed in terms of constraints on couplings of the heavy vector-boson triplet to quarks, leptons, and the Higgs boson. The data exclude a heavy vector-boson triplet with mass below 5.5 TeV in a weakly coupled scenario and 4.5 TeV in a strongly coupled scenario, as well as a Kaluza-Klein graviton with mass below 2.3 TeV.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Reducing memory cost of exact diagonalization using singular value decomposition
Not Available
Weinstein, Marvin↗
Observation of Spin Correlation in t(t)over-bar Events from pp Collisions at root s=7 TeV Using the ATLAS Detector
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Evidence for B - → τ - ν ¯ τ with a Hadronic Tagging Method Using the Full Data Sample of Belle
In this work, we measure the branching fraction of B - → τ - ν ¯ τ using the full Υ ( 4 S ) data sample containing 772 × 10 6 B B ¯ pairs collected with the Belle detector at the KEKB asymmetric-energy e + e - collider. Events with B B ¯ pairs are tagged by reconstructing one of the B mesons decaying into hadronic final states, and B - → τ - ν ¯ τ candidates are detected in the recoil. We discover evidence for B - → τ - ν ¯ τ with a significance of 3.0 standard deviations including systematic errors and measure a branching fraction B ( B - → τ - ν ¯ τ ) = [ 0.72 - 0.25 + 0.27 ( stat ) ± 0.11 ( syst ) ] × 10 - 4 .
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Precision Control of the Electron Longitudinal Bunch Shape Using an Emittance-Exchange Beam Line
We report on the experimental generation of relativistic electron bunches with a tunable longitudinal bunch shape. A longitudinal bunch-shaping (LBS) beam line, consisting of a transverse mask followed by a transverse-to-longitudinal emittance exchange (EEX) beam line, is used to tailor the longitudinal bunch shape (or current profile) of the electron bunch. The mask shapes the bunch’s horizontal profile, and the EEX beam line converts it to a corresponding longitudinal profile. The Argonne wakefield accelerator rf photoinjector delivers electron bunches into a LBS beamline to generate a variety of longitudinal bunch shapes. The quality of the longitudinal bunch shape is limited by various perturbations in the exchange process. We develop a simple method, based on the incident slope of the bunch, to significantly suppress the perturbations
Ha, G.↗
Probing the Single-Particle Character of Rotational States in F 19 Using a Short-Lived Isomeric Beam
A beam containing a substantial component of both the J π = 5 + , T 1 / 2 = 162 ns isomeric state of F 18 and its 1 + , 109.77-min ground state is utilized to study members of the ground-state rotational band in F 19 through the neutron transfer reaction ( d , p ) in inverse kinematics. The resulting spectroscopic strengths confirm the single-particle nature of the 13 / 2 + band-terminating state. The agreement between shell-model calculations using an interaction constructed within the s d shell, and our experimental results reinforces the idea of a single-particle–collective duality in the descriptions of the structure of atomic nuclei.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Photoproduction of the f 2 ( 1270 ) Meson Using the CLAS Detector
The quark structure of the f 2 ( 1270 ) meson has, for many years, been assumed to be a pure quark-antiquark (q$\bar{q}$) resonance with quantum numbers J PC = 2 ++ . Recently, it was proposed that the f 2 ( 1270 ) is a molecular state made from the attractive interaction of two ρ mesons. Such a state would be expected to decay strongly to final states with charged pions due to the dominant decay ρ → π + π - , whereas decay to two neutral pions would likely be suppressed. Here, we measure for the first time the reaction γp → π 0 π 0 p , using the CEBAF Large Acceptance Spectrometer detector at Jefferson Lab for incident beam energies between 3.6 and 5.4 GeV. Differential cross sections, dσ/dt , for f 2 ( 1270 ) photoproduction are extracted with good precision due to low backgrounds and are compared to theoretical calculations.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Structure of the complex between teicoplanin and a bacterial cell-wall peptide: use of a carrier-protein approach
Abstract not provided
Economou, Nicoleta J↗
Qu-antitative analysis of diffraction by liquids using a pink-spectrum X-ray source
Explore the source record for details and available documents.
Singh, Saransh↗
Identifying, studying and making good use of macromolecular crystals
As technology advances, the crystal volume that can be used to collect useful X-ray diffraction data decreases. The technologies available to detect and study growing crystals beyond the optical resolution limit and methods to successfully place the crystal into the X-ray beam are discussed. Structural biology has contributed tremendous knowledge to the understanding of life on the molecular scale. The Protein Data Bank, a depository of this structural knowledge, currently contains over 100 000 protein structures, with the majority stemming from X-ray crystallography. As the name might suggest, crystallography requires crystals. As detectors become more sensitive and X-ray sources more intense, the notion of a crystal is gradually changing from one large enough to embellish expensive jewellery to objects that have external dimensions of the order of the wavelength of visible light. Identifying these crystals is a prerequisite to their study. This paper discusses developments in identifying these crystals during crystallization screening and distinguishing them from other potential outcomes. The practical aspects of ensuring that once a crystal is identified it can then be positioned in the X-ray beam for data collection are also addressed.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
A Big Data Analytics Framework for HPC Log Data: Three Case Studies Using the Titan Supercomputer Log
Reliability, availability and serviceability (RAS) logs of high performance computing (HPC) resources, when closely investigated in spatial and temporal dimensions, can provide invaluable information regarding system status, performance, and resource utilization. These data are often generated from multiple logging systems and sensors that cover many components of the system. The analysis of these data for finding persistent temporal and spatial insights faces two main difficulties: the volume of RAS logs makes manual inspection difficult and the unstructured nature and unique properties of log data produced by each subsystem adds another dimension of difficulty in identifying implicit correlation among recorded events. To address these issues, we recently developed a multi-user Big Data analytics framework for HPC log data at Oak Ridge National Laboratory (ORNL). This paper introduces three in-progress data analytics projects that leverage this framework to assess system status, mine event patterns, and study correlations between user applications and system events. We describe the motivation of each project and detail their workflows using three years of log data collected from ORNL's Titan supercomputer.
Park, Byung↗