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
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
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 . It can separate the prompt and displaced
charm components. In Pb 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 Pb 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/ 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
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
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
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-: how to relate exclusive measurements to PDFs based on evolution equations
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 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- 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
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 , 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 of G-dwarf stars, and
of K-dwarf stars.Comment: 20 pages, 10 figures. Submitted to ApJ. This version has been
reviewed by a refere
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