1,256 research outputs found

    Resource Control for Synchronous Cooperative Threads

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    We develop new methods to statically bound the resources needed for the execution of systems of concurrent, interactive threads. Our study is concerned with a \emph{synchronous} model of interaction based on cooperative threads whose execution proceeds in synchronous rounds called instants. Our contribution is a system of compositional static analyses to guarantee that each instant terminates and to bound the size of the values computed by the system as a function of the size of its parameters at the beginning of the instant. Our method generalises an approach designed for first-order functional languages that relies on a combination of standard termination techniques for term rewriting systems and an analysis of the size of the computed values based on the notion of quasi-interpretation. We show that these two methods can be combined to obtain an explicit polynomial bound on the resources needed for the execution of the system during an instant. As a second contribution, we introduce a virtual machine and a related bytecode thus producing a precise description of the resources needed for the execution of a system. In this context, we present a suitable control flow analysis that allows to formulte the static analyses for resource control at byte code level

    Reducing model bias in a deep learning classifier using domain adversarial neural networks in the MINERvA experiment

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    We present a simulation-based study using deep convolutional neural networks (DCNNs) to identify neutrino interaction vertices in the MINERvA passive targets region, and illustrate the application of domain adversarial neural networks (DANNs) in this context. DANNs are designed to be trained in one domain (simulated data) but tested in a second domain (physics data) and utilize unlabeled data from the second domain so that during training only features which are unable to discriminate between the domains are promoted. MINERvA is a neutrino-nucleus scattering experiment using the NuMI beamline at Fermilab. AA-dependent cross sections are an important part of the physics program, and these measurements require vertex finding in complicated events. To illustrate the impact of the DANN we used a modified set of simulation in place of physics data during the training of the DANN and then used the label of the modified simulation during the evaluation of the DANN. We find that deep learning based methods offer significant advantages over our prior track-based reconstruction for the task of vertex finding, and that DANNs are able to improve the performance of deep networks by leveraging available unlabeled data and by mitigating network performance degradation rooted in biases in the physics models used for training.Comment: 41 page

    Search for associated Higgs boson production using like charge dilepton events in p(p)over-bar collisions at root s=1.96 TeV

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    We present a search for associated Higgs boson production in the process p (p) over bar -> W/ZH -> l(+/-)l'(+/-) + X in ee, e mu, and mu mu final states. The search is based on data collected by the D0 experiment at the Fermilab Tevatron Collider at root s = 1.96 TeV corresponding to 5.3 fb(-1) of integrated luminosity. We require two isolated leptons (electrons or muons) with the same electric charge and additional kinematic requirements. No significant excess above background is observed, and we set 95% C. L. observed (expected) upper limits on ratio of the production cross section to the standard model prediction of 6.4 (7.3) for a Higgs boson mass of 165 GeV and 13.5 (19.8) for a mass of 115 GeV

    Measurement of Total and Differential Cross Sections of Neutrino and Antineutrino Coherent π±\pi^\pm Production on Carbon

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    Neutrino induced coherent charged pion production on nuclei, ν‾μA→μ±π∓A\overline{\nu}_\mu A\to\mu^\pm\pi^\mp A, is a rare inelastic interaction in which the four-momentum squared transfered to the nucleus is nearly zero, leaving it intact. We identify such events in the scintillator of MINERvA by reconstructing |t| from the final state pion and muon momenta and by removing events with evidence of energetic nuclear recoil or production of other final state particles. We measure the total neutrino and antineutrino cross sections as a function of neutrino energy between 2 and 20 GeV and measure flux integrated differential cross sections as a function of Q2Q^2, EπE_\pi and θπ\theta_\pi. The Q2Q^2 dependence and equality of the neutrino and anti-neutrino cross-sections at finite Q2Q^2 provide a confirmation of Adler's PCAC hypothesis

    Determination of the Parity of the Neutral Pion via the Four-Electron Decay

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    We present a new determination of the parity of the neutral pion via the double Dalitz decay pi^0 -> e+ e- e+ e-. Our sample, which consists of 30511 candidate decays, was collected from K_L -> pi0 pi0 pi0 decays in flight at the KTeV-E799 experiment at Fermi National Accelerator Laboratory. We confirm the negative pi^0 parity, and place a limit on scalar contributions to the pi^0 -> e+ e- e+ e- decay amplitude of less than 3.3% assuming CPT conservation. The pi^0 gamma* gamma* form factor is well described by a momentum-dependent model with a slope parameter fit to the final state phase space distribution. Additionally, we have measured the branching ratio of this mode to be B(pi^0 -> e+ e- e+ e-) = (3.26 +- 0.18) x 10^(-5).Comment: 5 pages, 4 figures. Typographical error in radiative branching ratio (Eq. 6) correcte

    MINERvA neutrino detector response measured with test beam data

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    The MINERvA collaboration operated a scaled-down replica of the solid scintillator tracking and sampling calorimeter regions of the MINERvA detector in a hadron test beam at the Fermilab Test Beam Facility. This article reports measurements with samples of protons, pions, and electrons from 0.35 to 2.0 GeV/c momentum. The calorimetric response to protons, pions, and electrons are obtained from these data. A measurement of the parameter in Birks' law and an estimate of the tracking efficiency are extracted from the proton sample. Overall the data are well described by a Geant4-based Monte Carlo simulation of the detector and particle interactions with agreements better than 4%, though some features of the data are not precisely modeled. These measurements are used to tune the MINERvA detector simulation and evaluate systematic uncertainties in support of the MINERvA neutrino cross section measurement program.Comment: as accepted by NIM

    Search for the Rare Decays KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-

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    The KTeV E799 experiment has conducted a search for the rare decays KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-, where the X0 is a possible new neutral boson that was reported by the HyperCP experiment with a mass of (214.3 pm 0.5) MeV/c^{2}. We find no evidence for either decay. We obtain upper limits of Br(KL->pi0pi0X0->pi0pi0mu+mu-) pi0pi0mu+mu-) < 9.2 x 10^{-11} at the 90% confidence level. This result rules out the pseudoscalar X0 as an explanation of the HyperCP result under the scenario that the \bar{d}sX0 coupling is completely real

    Search for the Rare Decay K_{L}\to\pi^{0}\pi^{0}\gamma

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    The KTeV E799 experiment has conducted a search for the rare decay KL→π0π0γK_{L}\to\pi^{0}\pi^{0}\gamma via the topology KL→π0πD0γK_{L}\to\pi^{0}\pi^{0}_D\gamma (where πD0→γe+e−\pi^0_D\to\gamma e^+e^-). Due to Bose statistics of the π0\pi^0 pair and the real nature of the photon, the KL→π0π0γK_{L}\to\pi^{0}\pi^{0}\gamma decay is restricted to proceed at lowest order by the CP conserving direct emission (DE) of an E2 electric quadrupole photon. The rate of this decay is interesting theoretically since chiral perturbation theory predicts that this process vanishes at level O(p4)O(p^4). Therefore, this mode probes chiral perturbation theory at O(p6)O(p^6). In this paper we report a determination of an upper limit of 2.43×10−72.43\times 10^{-7} (90% CL) for KL→π0π0γK_{L}\to\pi^{0}\pi^{0}\gamma. This is approximately a factor of 20 lower than previous results.Comment: six pages and six figures in the submission. Reformatted for Physics Review

    Detailed Study of the KL -> 3pi0 Dalitz Plot

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    Using a sample of 68 million KL -> 3pi0 decays collected in 1996-1999 by the KTeV (E832) experiment at Fermilab, we present a detailed study of the KL -> 3pi0 Dalitz plot density. We report the first observation of interference from KL->pi+pi-pi0 decays in which pi+pi- rescatters to 2pi0 in a final-state interaction. This rescattering effect is described by the Cabibbo-Isidori model, and it depends on the difference in pion scattering lengths between the isospin I=0 and I=2 states, a0-a2. Using the Cabibbo-Isidori model, we present the first measurement of the KL-> 3pi0 quadratic slope parameter that accounts for the rescattering effect.Comment: accepted by Phys. Rev
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