50,042 research outputs found
Resource requirements and speed versus geometry of unconditionally secure physical key exchanges
The imperative need for unconditional secure key exchange is expounded by the
increasing connectivity of networks and by the increasing number and level of
sophistication of cyberattacks. Two concepts that are information theoretically
secure are quantum key distribution (QKD) and Kirchoff-law-Johnson-noise
(KLJN). However, these concepts require a dedicated connection between hosts in
peer-to-peer (P2P) networks which can be impractical and or cost prohibitive. A
practical and cost effective method is to have each host share their respective
cable(s) with other hosts such that two remote hosts can realize a secure key
exchange without the need of an additional cable or key exchanger. In this
article we analyze the cost complexities of cable, key exchangers, and time
required in the star network. We mentioned the reliability of the star network
and compare it with other network geometries. We also conceived a protocol and
equation for the number of secure bit exchange periods needed in a star
network. We then outline other network geometries and trade-off possibilities
that seem interesting to explore.Comment: 13 pages, 7 figures, MDPI Entrop
CP violation with a dynamical Higgs
We determine the complete set of independent gauge and gauge-Higgs CP-odd
effective operators for the generic case of a dynamical Higgs, up to four
derivatives in the chiral expansion. The relation with the linear basis of
dimension six CP-odd operators is clarified. Phenomenological applications
include bounds inferred from electric dipole moment limits, and from present
and future collider data on triple gauge coupling measurements and Higgs
signals.Comment: 41 pages, 3 figures; V2: citations added, typos corrected, version
published on JHE
Solar Model Parameters and Direct Measurements of Solar Neutrino Fluxes
We explore a novel possibility of determining the solar model parameters,
which serve as input in the calculations of the solar neutrino fluxes, by
exploiting the data from direct measurements of the fluxes. More specifically,
we use the rather precise value of the neutrino flux, obtained
from the global analysis of the solar neutrino and KamLAND data, to derive
constraints on each of the solar model parameters on which depends. We
also use more precise values of and fluxes as can be obtained from
future prospective data and discuss whether such measurements can help in
reducing the uncertainties of one or more input parameters of the Standard
Solar Model.Comment: 25 pages, 3 figure
Physical constraints on interacting dark energy models
Physical limits on the equation-of-state (EoS) parameter of a dark energy
component non-minimally coupled with the dark matter field are examined in
light of the second law of thermodynamics and the positiveness of entropy. Such
constraints are combined with observational data sets of type Ia supernovae,
baryon acoustic oscillations and the angular acoustic scale of the cosmic
microwave background to impose restrictions on the behaviour of the dark
matter/dark energy interaction. Considering two EoS parameterisations of the
type , we derive a general expression for the evolution
of the dark energy density and show that the combination of thermodynamic
limits and observational data provide tight bounds on the parameter
space.Comment: 7 pages, 4 figures. Accepted for publication in European Physical
Journal
The properties of attractors of canalyzing random Boolean networks
We study critical random Boolean networks with two inputs per node that
contain only canalyzing functions. We present a phenomenological theory that
explains how a frozen core of nodes that are frozen on all attractors arises.
This theory leads to an intuitive understanding of the system's dynamics as it
demonstrates the analogy between standard random Boolean networks and networks
with canalyzing functions only. It reproduces correctly the scaling of the
number of nonfrozen nodes with system size. We then investigate numerically
attractor lengths and numbers, and explain the findings in terms of the
properties of relevant components. In particular we show that canalyzing
networks can contain very long attractors, albeit they occur less often than in
standard networks.Comment: 9 pages, 8 figure
Moving embedded lattice solitons
It was recently proved that isolated unstable "embedded lattice solitons"
(ELS) may exist in discrete systems. The discovery of these ELS gives rise to
relevant questions such as the following: are there continuous families of
ELS?, can ELS be stable?, is it possible for ELS to move along the lattice?,
how do ELS interact?. The present work addresses these questions by showing
that a novel differential-difference equation (a discrete version of a complex
mKdV equation) has a two-parameter continuous family of exact ELS. The
numerical tests reveal that these solitons are stable and robust enough to
withstand collisions. The model may apply to the description of a Bose-Einstein
condensate with dipole-dipole interactions between the atoms, trapped in a deep
optical-lattice potential.Comment: 13 pages, 11 figure
Disentangling a dynamical Higgs
The pattern of deviations from Standard Model predictions and couplings is
different for theories of new physics based on a non-linear realization of the
gauge symmetry breaking and those assuming a linear
realization. We clarify this issue in a model-independent way via its effective
Lagrangian formulation in the presence of a light Higgs particle, up to first
order in the expansions: dimension-six operators for the linear expansion and
four derivatives for the non-linear one. Complete sets of pure gauge and
gauge-Higgs operators are considered, implementing the renormalization
procedure and deriving the Feynman rules for the non-linear expansion. We
establish the theoretical relation and the differences in physics impact
between the two expansions. Promising discriminating signals include the
decorrelation in the non-linear case of signals correlated in the linear one:
some pure gauge versus gauge-Higgs couplings and also between couplings with
the same number of Higgs legs. Furthermore, anomalous signals expected at first
order in the non-linear realization may appear only at higher orders of the
linear one, and vice versa. We analyze in detail the impact of both type of
discriminating signals on LHC physics.Comment: Version published in JHE
Excitons in coupled InAs/InP self-assembled quantum wires
Optical transitions in coupled InAs/InP self-assembled quantum wires are
studied within the single-band effective mass approximation including effects
due to strain. Both vertically and horizontally coupled quantum wires are
investigated and the ground state, excited states and the photoluminescence
peak energies are calculated. Where possible we compare with available
photo-luminescence data from which it was possible to determine the height of
the quantum wires. An anti-crossing of the energy of excited states is found
for vertically coupled wires signaling a change of symmetry of the exciton
wavefunction. This crossing is the signature of two different coupling regimes.Comment: 8 pages, 8 figures. To appear in Physical Review
Spectral Evolution of Two High-Energy Gamma-Ray Bursts
The prompt emission of the gamma-ray bursts is found to be very energetic,
releasing ~10^51 ergs in a flash. However, their emission mechanism remains
unclear and understanding their spectra is a key to determining the emission
mechanism. Many GRB spectra have been analyzed in the sub-MeV energy band, and
are usually well described with a smoothly broken power-law model. We present a
spectral analysis of two bright bursts (GRB910503 and GRB930506), using BATSE
and EGRET spectra that cover more than four decades of energy (30 keV - 200
MeV). Our results show time evolutions of spectral parameters (low-energy &
high-energy photon indices and break energy) that are difficult to reconcile
with a simple shock-acceleration model.Comment: 8 pages, 2 figures, to appear in the proceedings of "Astrophysical
Particle Acceleration in Geospace and Beyond", Chattanooga, 2002, AGU
monograp
Big Data and Analysis of Data Transfers for International Research Networks Using NetSage
Modern science is increasingly data-driven and collaborative in nature. Many scientific disciplines, including genomics, high-energy physics, astronomy, and atmospheric science, produce petabytes of data that must be shared with collaborators all over the world. The National Science Foundation-supported International Research Network Connection (IRNC) links have been essential to enabling this collaboration, but as data sharing has increased, so has the amount of information being collected to understand network performance. New capabilities to measure and analyze the performance of international wide-area networks are essential to ensure end-users are able to take full advantage of such infrastructure for their big data applications. NetSage is a project to develop a unified, open, privacy-aware network measurement, and visualization service to address the needs of monitoring today's high-speed international research networks. NetSage collects data on both backbone links and exchange points, which can be as much as 1Tb per month. This puts a significant strain on hardware, not only in terms storage needs to hold multi-year historical data, but also in terms of processor and memory needs to analyze the data to understand network behaviors. This paper addresses the basic NetSage architecture, its current data collection and archiving approach, and details the constraints of dealing with this big data problem of handling vast amounts of monitoring data, while providing useful, extensible visualization to end users
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