77,248 research outputs found
Global behavior of cosmological dynamics with interacting Veneziano ghost
In this paper, we shall study the dynamical behavior of the universe
accelerated by the so called Veneziano ghost dark energy component locally and
globally by using the linearization and nullcline method developed in this
paper. The energy density is generalized to be proportional to the Hawking
temperature defined on the trapping horizon instead of Hubble horizon of the
Friedmann-Robertson-Walker (FRW) universe. We also give a prediction of the
fate of the universe and present the bifurcation phenomenon of the dynamical
system of the universe. It seems that the universe could be dominated by dark
energy at present in some region of the parameter space.Comment: 8 pages, 7 figures, accepted for publication in JHE
Test of the Universality of Naive-time-reversal-odd Fragmentation Functions
We investigate the ''spontaneous'' hyperon transverse polarization in
annihilation and semi-inclusive deep inelastic scattering processes as
a test of the universality of the naive-time-reversal-odd transverse momentum
dependent fragmentation functions. We find that universality implies definite
sign relations among various observables. This provides a unique opportunity to
study initial/final state interaction effects in the fragmentation process and
test the associated factorization.Comment: 4 pages, 3 figure
Achieving precise mechanical control in intrinsically noisy systems
How can precise control be realized in intrinsically noisy systems? Here, we develop a general theoretical framework that provides a way of achieving precise control in signal-dependent noisy environments. When the control signal has Poisson or supra-Poisson noise, precise control is not possible. If, however, the control signal has sub-Poisson noise, then precise control is possible. For this case, the precise control solution is not a function, but a rapidly varying random process that must be averaged with respect to a governing probability density functional. Our theoretical approach is applied to the control of straight-trajectory arm movement. Sub-Poisson noise in the control signal is shown to be capable of leading to precise control. Intriguingly, the control signal for this system has a natural counterpart, namely the bursting pulses of neurons-trains of Dirac-delta functions-in biological systems to achieve precise control performance
Generalized Background-Field Method
The graphical method discussed previously can be used to create new gauges
not reachable by the path-integral formalism. By this means a new gauge is
designed for more efficient two-loop QCD calculations. It is related to but
simpler than the ordinary background-field gauge, in that even the triple-gluon
vertices for internal lines contain only four terms, not the usual six. This
reduction simplifies the calculation inspite of the necessity to include other
vertices for compensation. Like the ordinary background-field gauge, this
generalized background-field gauge also preserves gauge invariance of the
external particles. As a check of the result and an illustration for the
reduction in labour, an explicit calculation of the two-loop QCD
-function is carried out in this new gauge. It results in a saving of
45% of computation compared to the ordinary background-field gauge.Comment: 17 pages, Latex, 18 figures in Postscrip
Shifting the Quantum-Classical Boundary: Theory and Experiment for Statistically Classical Optical Fields
The growing recognition that entanglement is not exclusively a quantum
property, and does not even originate with Schr\"odinger's famous remark about
it [Proc. Camb. Phil. Soc. 31, 555 (1935)], prompts examination of its role in
marking the quantum-classical boundary. We have done this by subjecting
correlations of classical optical fields to new Bell-analysis experiments, and
report here values of the Bell parameter greater than . This
is many standard deviations outside the limit established by the
Clauser-Horne-Shimony-Holt (CHSH) Bell inequality [Phys. Rev. Lett. 23, 880
(1969)], in agreement with our theoretical classical prediction, and not far
from the Tsirelson limit . These results cast a new light
on the standard quantum-classical boundary description, and suggest a
reinterpretation of it.Comment: Comments and Remarks are warmly welcome! arXiv admin note: text
overlap with arXiv:1406.333
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A review of microgrid development in the United States – A decade of progress on policies, demonstrations, controls, and software tools
Microgrids have become increasingly popular in the United States. Supported by favorable federal and local policies, microgrid projects can provide greater energy stability and resilience within a project site or community. This paper reviews major federal, state, and utility-level policies driving microgrid development in the United States. Representative U.S. demonstration projects are selected and their technical characteristics and non-technical features are introduced. The paper discusses trends in the technology development of microgrid systems as well as microgrid control methods and interactions within the electricity market. Software tools for microgrid design, planning, and performance analysis are illustrated with each tool's core capability. Finally, the paper summarizes the successes and lessons learned during the recent expansion of the U.S. microgrid industry that may serve as a reference for other countries developing their own microgrid industries
Origins of Hidden Sector Dark Matter I: Cosmology
We present a systematic cosmological study of a universe in which the visible
sector is coupled, albeit very weakly, to a hidden sector comprised of its own
set of particles and interactions. Assuming that dark matter (DM) resides in
the hidden sector and is charged under a stabilizing symmetry shared by both
sectors, we determine all possible origins of weak-scale DM allowed within this
broad framework. We show that DM can arise only through a handful of
mechanisms, lending particular focus to Freeze-Out and Decay and Freeze-In, as
well as their variations involving late time re-annihilations of DM and DM
particle anti-particle asymmetries. Much like standard Freeze-Out, where the
abundance of DM depends only on the annihilation cross-section of the DM
particle, these mechanisms depend only on a very small subset of physical
parameters, many of which may be measured directly at the LHC. In particular,
we show that each DM production mechanism is associated with a distinctive
window in lifetimes and cross-sections for particles which may be produced in
the near future. We evaluate prospects for employing the LHC to definitively
reconstruct the origin of DM in a companion paper.Comment: 32 pages, 19 figures; v2: references added, published versio
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