81 research outputs found
Pdf's of Derivatives and Increments for Decaying Burgers Turbulence
A Lagrangian method is used to show that the power-law with a -7/2 exponent
in the negative tail of the pdf of the velocity gradient and of velocity
increments, predicted by E, Khanin, Mazel and Sinai (1997 Phys. Rev. Lett. 78,
1904) for forced Burgers turbulence, is also present in the unforced case. The
theory is extended to the second-order space derivative whose pdf has power-law
tails with exponent -2 at both large positive and negative values and to the
time derivatives. Pdf's of space and time derivatives have the same
(asymptotic) functional forms. This is interpreted in terms of a "random Taylor
hypothesis".Comment: LATEX 8 pages, 3 figures, to appear in Phys. Rev.
Structure of TiAlN Reactive Sputtered Coatings
The Raman spectra, X-ray diffraction and hardness of the TiAlN films co-deposited on the steel substrates
by reactive sputtering from Ti and Al targets in a mixture of N2 + Ar gas with two magnetrons at
room temperature have been studied. From Raman spectra it is found that the position of high-frequency
bands in vibrational spectra was located at 700-730 cm 1 or in the region of 830 850 cm 1 depending on
the deposition parameters whereas it is not exceed 630 cm 1 from TiAlN of NaCl structure. It is found the
two-phase structure of coatings: a small quantity of NaCl-type structure of TiAlN (TiN) and the disordered
structure of the chains of polyhedra [TiNx] with x = 5 and x = 4. The chains of polyhedra [TiNx] with x = 4
are mainly formed at large discharge power of Al(Ti) target or at small content of N2 gas.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2492
Fine tuned vortices in lattice SU(2) gluodynamics
We report measurements of the action associated with center vortices in SU(2)
pure lattice gauge theory. In the lattice units the excess of the action on the
plaquettes belonging to the vortex is approximately a constant, independent on
the lattice spacing 'a'. Therefore the action of the center vortex is of order
'A/a^2', where 'A' is its area. Since the area 'A' is known to scale in the
physical units, the measurements imply that the suppression due to the surface
action is balanced, or fine tuned to the entropy factor which is to be an
exponential of 'A/a^2'.Comment: Version accepted for publication in PLB, stylistic change
Twisted sectors in three-dimensional gravity
Twisted sectors --solutions to the equations of motion with non-trivial
monodromies-- of three dimensional Euclidean gravity are studied. We argue that
upon quantization this new sector of the theory provides the necessary (and no
more) degrees of freedom to account for the Bekenstein-Hawking entropy.Comment: An unnecessary restriction removed. To appear in PRD. Revtex, no
figures, 20 p
Two-dimensional Quantum-Corrected Eternal Black Hole
The one-loop quantum corrections to geometry and thermodynamics of black hole
are studied for the two-dimensional RST model. We chose boundary conditions
corresponding to the eternal black hole being in the thermal equilibrium with
the Hawking radiation. The equations of motion are exactly integrated. The one
of the solutions obtained is the constant curvature space-time with dilaton
being a constant function. Such a solution is absent in the classical theory.
On the other hand, we derive the quantum-corrected metric (\ref{solution})
written in the Schwarzschild like form which is a deformation of the classical
black hole solution \cite{5d}. The space-time singularity occurs to be milder
than in classics and the solution admits two asymptotically flat black hole
space-times lying at "different sides" of the singularity. The thermodynamics
of the classical black hole and its quantum counterpart is formulated. The
thermodynamical quantities (energy, temperature, entropy) are calculated and
occur to be the same for both the classical and quantum-corrected black holes.
So, no quantum corrections to thermodynamics are observed. The possible
relevance of the results obtained to the four-dimensional case is discussed.Comment: Latex, 28 pges; minor corrections in text and abstract made and new
references adde
Anomalously localized states and multifractal correlations of critical wavefunctions in two-dimensional electron systems with spin-orbital interactions
Anomalously localized states (ALS) at the critical point of the Anderson
transition are studied for the SU(2) model belonging to the two-dimensional
symplectic class. Giving a quantitative definition of ALS to clarify
statistical properties of them, the system-size dependence of a probability to
find ALS at criticality is presented. It is found that the probability
increases with the system size and ALS exist with a finite probability even in
an infinite critical system, though the typical critical states are kept to be
multifractal. This fact implies that ALS should be eliminated from an ensemble
of critical states when studying critical properties from distributions of
critical quantities. As a demonstration of the effect of ALS to critical
properties, we show that the distribution function of the correlation dimension
of critical wavefunctions becomes a delta function in the thermodynamic limit
only if ALS are eliminated.Comment: 7 pages, 6 figure
Positive specific heat of the quantum corrected dilaton black hole
Path integral quantization of dilaton gravity in two dimensions is applied to
the CGHS model to the first nontrivial order in matter loops. Our approach is
background independent as geometry is integrated out exactly. The result is an
effective shift of the Killing norm: the apparent horizon becomes smaller. The
Hawking temperature which is constant to leading order receives a quantum
correction. As a consequence, the specific heat becomes positive and
proportional to the square of the black hole mass.Comment: 18 pages, JHEP style, 1 eps figure, v2: extended the discussion,
added new formulas for mass change, added three new references (in particular
[35]
Statistique mensuelle de la viande. 1968 N° 4 APRIL-AVRIL = Monthly statistiques of meat. 1968 No. 4 April
In high energy experiments such as active beam dump searches for rare decays and missing energy events, the beam purity is a crucial parameter. In this paper we present a technique to reject heavy charged particle contamination in the 100 GeV electron beam of the H4 beam line at CERN SPS. The method is based on the detection with BGO scintillators of the synchrotron radiation emitted by the electrons passing through a bending dipole magnet. A 100 GeV pi- beam is used to test the method in the NA64 experiment resulting in a suppression factor of 10−5 while the efficiency for electron detection is 95%. The spectra and the rejection factors are in very good agreement with the Monte Carlo simulation. The reported suppression factors are significantly better than previously achieved.ISSN:0168-9002ISSN:1872-957
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