2,501 research outputs found

    Inclusive J/psi and psi(2S) production in p-Pb collisions at sqrt(s_NN) = 5.02 TeV with ALICE at the LHC

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    We report on the inclusive J/psi nuclear modification factor in p-Pb collisions at sqrt(s_NN) = 5.02 TeV as a function of rapidity y and transverse momentum p_T. The experimental coverage extends down to p_T = 0 GeV/c in the three rapidity ranges accessible by ALICE (-4.46 < y_cms < -2.96, -1.37 < y_cms < 0.46, 2.03 < y_cms < 3.53). The obtained results as a function of rapidity are in agreement with theory predictions based only on shadowing or on coherent energy loss. At forward and backward rapidity, the psi(2S) measurement complements the J/psi results. The ratio between the psi(2S) and J/psi cross section is significantly smaller in p-Pb than in pp collisions in both rapidity regions.Comment: To appear in the proceedings of Hard-Probes 2013, the 6th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions, Nov. 201

    Heavy flavour production in proton-lead and lead-lead collisions with LHCb

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    The LHCb experiment offers the unique opportunity to study heavy-ion interactions in the forward region (2 <eta< 5), in a kinematic domain complementary to the other 3 large experiments at the LHC. The detector has excellent capabilities for reconstructing quarkonia and open charm states, including baryons, down to zero pTp_T. It can separate the prompt and displaced charm components. In ppPb collisions, both forward and backward rapidities are covered thanks to the possibility of beam reversal. Results include measurements of the nuclear modification factor and forward-backward ratio for charmonium, open charm and bottomonium states. These quantities are sensitive probes for nuclear effects in heavy flavour production. Perspectives are given with the large accumulated luminosity during the 2016 ppPb run at the LHC. In 2015, LHCb participated successfully for the first time in the PbPb data-taking. The status of the forward prompt J/ψ\psi nuclear modification factor measurement in lead-lead collisions is discussed.Comment: 4 pages, 3 Figures, proceedings for the XXVIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions, Quark Matter 2017 in Chicago from February 5 to February 11, 201

    Constructing Cost-Effective and Targetable ICS Honeypots Suited for Production Networks

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    Honeypots are a technique that can mitigate the risk of cyber threats. Effective honeypots are authentic and targetable, and their design and implementation must accommodate risk tolerance and financial constraints. The proprietary, and often expensive, hardware and software used by Industrial Control System (ICS) devices creates the challenging problem of building a flexible, economical, and scalable honeypot. This research extends Honeyd into Honeyd+, making it possible to use the proxy feature to create multiple high interaction honeypots with a single Programmable Logic Controller (PLC). Honeyd+ is tested with a network of 75 decoy PLCs, and the interactions with the decoys are compared to a physical PLC to test for authenticity. The performance test evaluates the impact of multiple simultaneous connections to the PLC. The functional test is successful in all cases. The performance test demonstrated that the PLC is a limiting factor, and that introducing Honeyd+ has a marginal impact on performance. Notable findings are that the Raspberry Pi is the preferred hosting platform, and more than five simultaneous connections were not optimal

    Sodium Absorption From the Exoplanetary Atmosphere of HD189733b Detected in the Optical Transmission Spectrum

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    We present the first ground-based detection of sodium absorption in the transmission spectrum of an extrasolar planet. Absorption due to the atmosphere of the extrasolar planet HD189733b is detected in both lines of the NaI doublet. High spectral resolution observations were taken of eleven transits with the High Resolution Spectrograph (HRS) on the 9.2 meter Hobby-Eberly Telescope (HET). The NaI absorption in the transmission spectrum due to HD189733b is (-67.2 +/- 20.7) x 10^-5 deeper in the ``narrow'' spectral band that encompasses both lines relative to adjacent bands. The 1-sigma error includes both random and systematic errors, and the detection is >3-sigma. This amount of relative absorption in NaI for HD189733b is ~3x larger than detected for HD209458b by Charbonneau et al. (2002), and indicates these two hot-Jupiters may have significantly different atmospheric properties.Comment: 12 pages, 2 figures; Accepted for publication in ApJ Letter

    Despatches from the Front: Recent Skirmishes Along the Frontiers of Electronic Contracting Law

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    This Article will provide a short overview of the current efforts in the United States and the European Union to reform contract law to accommodate recent innovations in electronic contracting. Whether changes are needed to current contract law doctrines governing contract formation, effectiveness of contract terms, choice of law and forum provisions, special protections for consumers, and signature and writing requirements, revisions in these areas have all proved controversial. Even in those areas where a consensus may be emerging on whether law reform may be appropriate in some form, consensus is often still lacking with regard to the specific legislation needed to accomplish those reforms. The United States is not the only major arena where such reforms are being debated. The EU is addressing the same problems, but taking a markedly different approach. If the United States and EU commit themselves to divergent approaches to the regulation of electronic contracting, major obstacles will be placed in the paths of businesses hoping to exploit global electronic markets. Businesses may then be forced to design their electronic commerce systems to conform to multiple, incompatible legal standards, or face the prospect of being shut out of major markets for electronic commerce services altogether

    Exclusive meets inclusive at small Bjorken-xBx_B: how to relate exclusive measurements to PDFs based on evolution equations

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    Exclusive heavy-vector-meson photoproduction is a prominent signal in collider experiments with hadron beams. At the highest photon-hadron collision energies, this process is considered as a candidate to constrain gluon parton distribution functions (PDFs) at small longitudinal momentum fractions. However, in the framework of collinear factorisation, exclusive particle production is described in terms of generalised parton distributions (GPDs). In this contribution, we investigate at the leading order in αs\alpha_s the connection between GPDs and PDFs. Our main result is a proposal to quantify the systematic uncertainty inherent to this connection. We put our approach into context with respect to the Shuavev transform. Our uncertainty estimate can be straightforwardly adapted to higher fixed orders and small-xx resummations. The question of extrapolating GPDs to vanishing skewness is paramount for the programme of the Electron Ion Collider (EIC), notably for the extraction of the radial distributions of partons.Comment: 17 pages, 7 figure

    A Study of the Shortest-Period Planets Found With Kepler

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    We present the results of a survey aimed at discovering and studying transiting planets with orbital periods shorter than one day (ultra--short-period, or USP, planets), using data from the {\em Kepler} spacecraft. We computed Fourier transforms of the photometric time series for all 200,000 target stars, and detected transit signals based on the presence of regularly spaced sharp peaks in the Fourier spectrum. We present a list of 106 USP candidates, of which 18 have not previously been described in the literature. In addition, among the objects we studied, there are 26 USP candidates that had been previously reported in the literature which do not pass our various tests. All 106 of our candidates have passed several standard tests to rule out false positives due to eclipsing stellar systems. A low false positive rate is also implied by the relatively high fraction of candidates for which more than one transiting planet signal was detected. By assuming these multi-transit candidates represent coplanar multi-planet systems, we are able to infer that the USP planets are typically accompanied by other planets with periods in the range 1-50 days, in contrast with hot Jupiters which very rarely have companions in that same period range. Another clear pattern is that almost all USP planets are smaller than 2 R⊕R_\oplus, possibly because gas giants in very tight orbits would lose their atmospheres by photoevaporation when subject to extremely strong stellar irradiation. Based on our survey statistics, USP planets exist around approximately (0.51±0.07)%(0.51\pm 0.07)\% of G-dwarf stars, and (0.83±0.18)%(0.83\pm 0.18)\% of K-dwarf stars.Comment: 20 pages, 10 figures. Submitted to ApJ. This version has been reviewed by a refere
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