644 research outputs found
A note on N=4 supersymmetric mechanics on K\"ahler manifolds
The geometric models of N=4 supersymmetric mechanics with
(2d.2d)_{\DC}-dimensional phase space are proposed, which can be viewed as
one-dimensional counterparts of two-dimensional N=2 supersymmetric sigma-models
by Alvarez-Gaum\'e and Freedman. The related construction of supersymmetric
mechanics whose phase space is a K\"ahler supermanifold is considered. Also,
its relation with antisymplectic geometry is discussed.Comment: 4 pages, revte
Brane gravity, higher derivative terms and non-locality
In brane world scenarios with a bulk scalar field between two branes it is
known that 4-dimensional Einstein gravity is restored at low energies on either
brane. By using a gauge-invariant gravitational and scalar perturbation
formalism we extend the theory of weak gravity in the brane world scenarios to
higher energies, or shorter distances. We argue that weak gravity on either
brane is indistinguishable from 4-dimensional higher derivative gravity,
provided that the inter-brane distance (radion) is stabilized, that the
background bulk scalar field is changing near the branes and that the
background bulk geometry near the branes is warped. This argument holds for a
general conformal transformation to a frame in which matter on the branes is
minimally coupled to the metric. In particular, Newton's constant and the
coefficients of curvature-squared terms in the 4-dimensional effective action
are determined up to an ambiguity of adding a Gauss-Bonnet topological term. In
other words, we provide the brane-world realization of the so called
-model without utilizing a quantum theory. We discuss the appearance of
composite spin-2 and spin-0 fields in addition to the graviton on the brane and
point out a possibility that the spin-0 field may play the role of an effective
inflaton to drive brane-world inflation. Finally, we conjecture that the
sequence of higher derivative terms is an infinite series and, thus, indicates
non-locality in the brane world scenarios.Comment: Latex, 18 pages; a comment on the spurious tensor mode was added;
recovery condition of higher derivative gravity clarifie
Anisotropy at the end of the cosmic ray spectrum?
The starburst galaxies M82 and NGC253 have been proposed as the primary
sources of cosmic rays with energies above eV. For energies \agt
10^{20.3} eV the model predicts strong anisotropies. We calculate the
probabilities that the latter can be due to chance occurrence. For the highest
energy cosmic ray events in this energy region, we find that the observed
directionality has less than 1% probability of occurring due to random
fluctuations. Moreover, during the first 5 years of operation at Auger, the
observation of even half the predicted anisotropy has a probability of less
than to occur by chance fluctuation. Thus, this model can be subject
to test at very small cost to the Auger priors budget and, whatever the outcome
of that test, valuable information on the Galactic magnetic field will be
obtained.Comment: Final version to be published in Physical Review
Analysis of the modes of energy consumption of the complex of an incoherent scattering of the institute of ionosphere of national academy of sciences and the ministry of education and science of Ukraine
У даній статті представлені результати аналізу режимів енергоспоживання комплексу некогерентного розсіяння Інституту іоносфери НАН і МОН України з метою вирішення проблеми підвищення енергоефективності науково-дослідного комплексу та створення енергоефективної системи електропостачання, яка забезпечить стійку роботу наукового обладнання для виконання дослідницьких програм НАН України. Описана система електроживлення комплексу та режими енергоспоживання комплексу. Описано пристрої радарної системи, а також найбільш потужні споживачі електроенергії, які споживають електроенергію на експериментальні і господарські потреби. Проаналізовано енергоспоживання комплексу некогерентного розсіяння за 2013 р. Отримано і представлено графіки середньої споживаної потужності (середньодобовий показник) і середньої споживаної потужності в режимі вимірювань. Описана доцільність проведення робіт з оптимізації енергопостачання науково-дослідного комплексу Інституту іоносфери. Запропоновано можливі заходи для зниження економічної вартості проведення експериментів з дослідження іоносфери науково-дослідного комплексу некогерентного розсіяння. Проведено аналіз робіт сучасних авторів з метою показати, що підвищення ефективності функціонування систем електропостачання є актуальною проблемою сучасних досліджень.This article presents the results of the analysis of the energy consumption modes of the incoherent scattering complex of the Institute of Ionosphere of the National Academy of Sciences and the Ministry of Education and Science of Ukraine to solve the problem of increasing the energy efficiency of a research complex and creating an energy efficient power supply system that will ensure the sustainability of scientific equipment for research programs
of the National Academy of Sciences of Ukraine. The system of power supply of the complex and modes of power consumption of the complex are described. The devices of the radar system are described, as well as the most powerful consumers of electricity, which consume electricity for experimental and economic needs. The energy consumption of the incoherent scattering complex in 2013 is analyzed. Graphs of the average power consumption (daily average) and average power consumption in measurement modes were obtained and presented. The feasibility of work to optimize the energy supply of the research complex of the institute of the ionosphere is described. Possible measures are proposed to reduce the economic cost of conducting experiments on the study of the ionosphere of an incoherent scattering research complex. The analysis of the works of modern authors i s
carried out in order to show that increasing the efficiency of the power supply systems is an actual problem of modern research
Studies of correlations between D and mesons in high energy photoproduction
Studies of correlations for a large sample of events containing
fully and partially reconstructed pairs of charmed mesons recorded by the
Fermilab photoproduction experiment FOCUS (FNAL-E831) are presented.
Correlations between and mesons are used to study heavy quark
production dynamics. We present results for fully and partially reconstructed
charm pairs and comparisons to a recent version of \textsc{Pythia} with default
parameter settings. We also comment on the production of in our
data.Comment: 14 pages, 4 figure
Global Search for New Physics with 2.0/fb at CDF
Data collected in Run II of the Fermilab Tevatron are searched for
indications of new electroweak-scale physics. Rather than focusing on
particular new physics scenarios, CDF data are analyzed for discrepancies with
the standard model prediction. A model-independent approach (Vista) considers
gross features of the data, and is sensitive to new large cross-section
physics. Further sensitivity to new physics is provided by two additional
algorithms: a Bump Hunter searches invariant mass distributions for "bumps"
that could indicate resonant production of new particles; and the Sleuth
procedure scans for data excesses at large summed transverse momentum. This
combined global search for new physics in 2.0/fb of ppbar collisions at
sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D
Rapid Communication
Observation of Orbitally Excited B_s Mesons
We report the first observation of two narrow resonances consistent with
states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar
collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the
Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed
as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+,
\bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1})
= 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
On the Holographic RG-flow and the Low-energy, Strong Coupling, Large N Limit
From the AdS/CFT correspondence, we learn that the classical evolution of
supergravity in the bulk can be reduced to a RG-flow equation for the dual
low-energy, strongly coupled and large N gauge theory on the boundary. This
result has been used to obtain interesting relations between the various terms
in the gravitational part of the boundary effective action, in particular the
term that affect the cosmological constant. It is found that once the
cosmological constant is cancelled in the UV theory, the RG-flow symmetry of
the boundary effective action automatically implies the existence of zero
cosmological constant solutions that extend all the way into the IR. Given the
standard (and well founded) contradiction between the RG-flow idea and the
observational evidence of a small cosmological constant, this is considered to
be an important progress, albeit incomplete, towards the final solution.
Motivated by this success, it would be interesting to see whether this
RG-stability extends outside the scope of strong 't Hooft coupling and large N
regime that are implicitly assumed in the de Boer-Verlinde-Verlinde
Hamilton-Jacobi formulation of the holographic RG-flow equations of the
boundary theory. In this paper, we address this question. Taking into account
the leading order corrections in the 1/N and parameters, we
derive new bulk/boundary relations, from which one can read all the local terms
in the boundary effective action. Next, we use the resulting constraints, to
examine whether the RG-stability of the cosmological constant extends to the
new coupling regime. It would be also interesting to use these constraints to
study the Randall-Sundrum scenario in this case.Comment: 27 pages, LateX, no figures, minor changes, typos corrected and added
more reference
The Superspace of Geometrodynamics
Wheeler's Superspace is the arena in which Geometrodynamics takes place. I
review some aspects of its geometrical and topological structure that Wheeler
urged us to take seriously in the context of canonical quantum gravity.Comment: 29 pages, 8 figures. To appear in the Wheeler memorial volume of
General Relativity and Gravitatio
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