4,017 research outputs found

    Measurement of the gamma gamma -> pi+ pi- and gamma gamma -> K+ K- processes at energies of 2.4 - 4.1 GeV

    Full text link
    We have measured pi+pi- and K+K- production in two-photon collisions using 87.7 /fb of data collected with the Belle detector at the asymmetric energy e+e- collider KEKB. The cross sections are measured to high precision in the two-photon center-of-mass energy (W) range between 2.4 GeV < W < 4.1 GeV and angular region |cos theta^{*}| < 0.6. The cross section ratio sigma(gammagamma->K+K-)/sigma(gammagamma->pi+pi-) is measured to be 0.89 +- 0.04(stat) +- 0.15(syst) in the range of 3.0 GeV < W < 4.1 GeV, where the ratio is energy independent. We observe a sin^{-4} theta^{*} behavior of the cross section in the same W range. Production of chi_{c0} and chi_{c2} mesons is observed in both gammagamma -> pi+pi- and gammagamma -> K+K- modes.Comment: 17 pages, 5 figures, submitted to Phys. Lett. B, errors relative to the two-photon decay width correcte

    OGLE-2017-BLG-0329L: A Microlensing Binary Characterized with Dramatically Enhanced Precision Using Data from Space-based Observations

    Get PDF
    Mass measurements of gravitational microlenses require one to determine the microlens parallax π E, but precise π E measurement, in many cases, is hampered due to the subtlety of the microlens-parallax signal combined with the difficulty of distinguishing the signal from those induced by other higher-order effects. In this work, we present the analysis of the binary-lens event OGLE-2017-BLG-0329, for which π E is measured with a dramatically improved precision using additional data from space-based Spitzer observations. We find that while the parallax model based on the ground-based data cannot be distinguished from a zero-π E model at the 2σ level, the addition of the Spitzer data enables us to identify two classes of solutions, each composed of a pair of solutions according to the well-known ecliptic degeneracy. It is found that the space-based data reduce the measurement uncertainties of the north and east components of the microlens-parallax vector π E by factors ~18 and ~4, respectively. With the measured microlens parallax combined with the angular Einstein radius measured from the resolved caustic crossings, we find that the lens is composed of a binary with component masses of either (M1, M2) ~ (1.1, 0.8) M⊙ or ~(0.4, 0.3) M⊙ according to the two solution classes. The first solution is significantly favored but the second cannot be securely ruled out based on the microlensing data alone. However, the degeneracy can be resolved from adaptive optics observations taken ~10 years after the event

    Dilepton mass spectra in p+p collisions at sqrt(s)= 200 GeV and the contribution from open charm

    Get PDF
    The PHENIX experiement has measured the electron-positron pair mass spectrum from 0 to 8 GeV/c^2 in p+p collisions at sqrt(s)=200 GeV. The contributions from light meson decays to e^+e^- pairs have been determined based on measurements of hadron production cross sections by PHENIX. They account for nearly all e^+e^- pairs in the mass region below 1 GeV/c^2. The e^+e^- pair yield remaining after subtracting these contributions is dominated by semileptonic decays of charmed hadrons correlated through flavor conservation. Using the spectral shape predicted by PYTHIA, we estimate the charm production cross section to be 544 +/- 39(stat) +/- 142(syst) +/- 200(model) \mu b, which is consistent with QCD calculations and measurements of single leptons by PHENIX.Comment: 375 authors from 57 institutions, 18 pages, 4 figures, 2 tables. Submitted to Physics Letters B. v2 fixes technical errors in matching authors to institutions. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Age-of-Information Aware Contents Caching and Distribution for Connected Vehicles

    Full text link
    To support rapid and accurate autonomous driving services, road environment information, which is difficult to obtain through vehicle sensors themselves, is collected and utilized through communication with surrounding infrastructure in connected vehicle networks. For this reason, we consider a scenario that utilizes infrastructure such as road side units (RSUs) and macro base station (MBS) in situations where caching of road environment information is required. Due to the rapidly changed road environment, a concept which represents a freshness of the road content, age of information (AoI), is important. Based on the AoI value, in the connected vehicle system, it is essential to keep appropriate content in the RSUs in advance, update it before the content is expired, and send the content to the vehicles which want to use it. However, too frequent content transmission for the minimum AoI leads to indiscriminate use of network resources. Furthermore, a transmission control, that content AoI and service delay are not properly considered adversely, affects user service. Therefore, it is important to find an appropriate compromise. For these reasons, the objective of this paper is about to reduce the system cost used for content delivery through the proposed system while minimizing the content AoI presented in MBS, RSUs and UVs. The transmission process, which is able to be divided into two states, i.e., content caching and service, is approached using Markov decision process (MDP) and Lyapunov optimization framework, respectively, which guarantee optimal solutions, as verified via data-intensive performance evaluation

    Study of B0ˉD()0π+π\bar{B^{0}} \to D^{(*)0} \pi^+ \pi^- Decays

    Get PDF
    We report on a study of B0ˉD()0π+π\bar{B^{0}} \to D^{(*) 0} \pi^+ \pi^- decays using 29.1 fb1^{-1} of e+ee^{+}e^{-} annihilation data recorded at the Υ(4S)\Upsilon(4S) resonance with the Belle detector at the KEKB storage ring. Making no assumptions about the intermediate mechanism, the branching fractions for Bˉ0D0π+π\bar{B}^0 \to D^0 \pi^+ \pi^- and Bˉ0D0π+π\bar{B}^0 \to D^{* 0} \pi^+ \pi^- are determined to be (8.0±0.6±1.5)×104(8.0 \pm 0.6 \pm 1.5) \times 10^{-4} and (6.2±1.2±1.8)×104 (6.2 \pm 1.2 \pm 1.8) \times 10^{-4} respectively. An analysis of B0ˉD0π+π\bar{B^{0}} \to D^{0} \pi^+ \pi^- candidates yields to the first observation of the color-suppressed hadronic decay Bˉ0D0ρ0\bar{B}^0 \to D^0 \rho^0 with the branching fraction (2.9±1.0±0.4)×104(2.9 \pm 1.0 \pm 0.4) \times 10^{-4}. We measure the ratio of branching fractions B(B0ˉD0ρ0)/B(B0ˉD0ω){\mathcal B}(\bar{B^0} \to D^0 \rho^0) / {\mathcal B}(\bar{B^0} \to D^0 \omega) = 1.6 ±\pm 0.8.Comment: 13 pages, LaTex, 4 figures, submitted to Phys. Lett.

    Classical non-Gaussianity from non-linear evolution of curvature perturbations

    Full text link
    We study the non-linear evolution of the curvature perturbations during matter dominated era. We show that regardless of the origin of the primordial perturbation, the Bardeen potential and curvature receive sizable contributions from the classical non-linear evolution effects, and quantify them exactly. On the super-horizon scales we have squeezed peak of the bispectrum with magnitude, in terms of the local non-linear parameters of Bardeen curvature, 1/6 < f_{NL} 19/15, and of Bardeen potential, -1/4 < f_{NL} < 7/5, depending on the configuration of momenta. On the sub-horizon scales the bispectrum show equilateral shape, and can serve as a potential probe of general relativity.Comment: (v1) 8 pages, 2 figures; (v2) 10 pages, more discussions and clarifications, including explicit comparison with other studie

    Brain structural covariance networks in obsessive-compulsive disorder: a graph analysis from the ENIGMA Consortium.

    Get PDF
    Brain structural covariance networks reflect covariation in morphology of different brain areas and are thought to reflect common trajectories in brain development and maturation. Large-scale investigation of structural covariance networks in obsessive-compulsive disorder (OCD) may provide clues to the pathophysiology of this neurodevelopmental disorder. Using T1-weighted MRI scans acquired from 1616 individuals with OCD and 1463 healthy controls across 37 datasets participating in the ENIGMA-OCD Working Group, we calculated intra-individual brain structural covariance networks (using the bilaterally-averaged values of 33 cortical surface areas, 33 cortical thickness values, and six subcortical volumes), in which edge weights were proportional to the similarity between two brain morphological features in terms of deviation from healthy controls (i.e. z-score transformed). Global networks were characterized using measures of network segregation (clustering and modularity), network integration (global efficiency), and their balance (small-worldness), and their community membership was assessed. Hub profiling of regional networks was undertaken using measures of betweenness, closeness, and eigenvector centrality. Individually calculated network measures were integrated across the 37 datasets using a meta-analytical approach. These network measures were summated across the network density range of K = 0.10-0.25 per participant, and were integrated across the 37 datasets using a meta-analytical approach. Compared with healthy controls, at a global level, the structural covariance networks of OCD showed lower clustering (P &lt; 0.0001), lower modularity (P &lt; 0.0001), and lower small-worldness (P = 0.017). Detection of community membership emphasized lower network segregation in OCD compared to healthy controls. At the regional level, there were lower (rank-transformed) centrality values in OCD for volume of caudate nucleus and thalamus, and surface area of paracentral cortex, indicative of altered distribution of brain hubs. Centrality of cingulate and orbito-frontal as well as other brain areas was associated with OCD illness duration, suggesting greater involvement of these brain areas with illness chronicity. In summary, the findings of this study, the largest brain structural covariance study of OCD to date, point to a less segregated organization of structural covariance networks in OCD, and reorganization of brain hubs. The segregation findings suggest a possible signature of altered brain morphometry in OCD, while the hub findings point to OCD-related alterations in trajectories of brain development and maturation, particularly in cingulate and orbitofrontal regions

    Health-related quality of life in KEYNOTE-010 : a phase II/III study of pembrolizumab versus docetaxel in patients with previously treated advanced, programmed death ligand 1-expressing NSCLC

    No full text
    Introduction: In the phase II/III KEYNOTE-010 study (ClinicalTrials.gov, NCT01905657), pembrolizumab significantly prolonged overall survival over docetaxel in patients with previously treated, programmed death ligand 1-expressing (tumor proportion score >= 1%), advanced NSCLC. Health-related quality of life (HRQoL) results are reported here. Methods: Patients were randomized 1:1:1 to pembrolizumab 2 or 10 mg/kg every 3 weeks or docetaxel 75 mg/m(2) every 3 weeks. HRQoL was assessed using European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLC) Core 30 (C30), EORTC QLQ-Lung Cancer 13 (LC13), and EuroQoL-5D. Key analyses included mean baseline-to-week-12 change in global health status (GHS)/quality of life (QoL) score, functioning and symptom domains, and time to deterioration in a QLQ-LC13 composite endpoint of cough, dyspnea, and chest pain. Results: Patient reported outcomes compliance was high across all three instruments. Pembrolizumab was associated with better QLQ-C30 GHS/QoL scores from baseline to 12 weeks than docetaxel, regardless of pembrolizumab dose or tumor proportion score status (not significant). Compared with docetaxel, fewer pembrolizumab-treated patients had "deteriorated" status and more had "improved" status in GHS/QoL. Nominally significant improvement was reported in many EORTC symptom domains with pembrolizumab, and nominally significant worsening was reported with docetaxel. Significant prolongation in true time to deterioration for the QLQ-LC13 composite endpoint emerged for pembrolizumab 10 mg/kg compared to docetaxel (nominal two-sided p = 0.03), but not for the 2-mg/kg dose. Conclusions: These findings suggest that HRQoL and symptoms are maintained or improved to a greater degree with pembrolizumab than with docetaxel in this NSCLC patient population. (C) 2019 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.
    corecore