21,218 research outputs found
Exclusive diffractive electroproduction of dijets in collinear factorization
Exclusive electroproduction of hard dijets can be described within the
collinear factorization. This process has clear experimental signature and
provides one with an interesting alternative venue to test QCD description of
hard diffractive processes and extract information on generalized nucleon
parton distributions. In this work we present detailed leading-order QCD
calculations of the relevant cross sections, including longitudinal momentum
fraction distribution of the dijets and their azimuthal angle dependence.Comment: 11 pages, 14 Postscript figures, uses revtex4.st
Non-dopplerian cosmological redshift parameters in a model of graviton-dusty universe
Possible effects are considered which would be caused by a hypothetical
superstrong interaction of photons or massive bodies with single gravitons of
the graviton background. If full cosmological redshift magnitudes are caused by
the interaction, then the luminosity distance in a flat non-expanding universe
as a function of redshift is very similar to the specific function which fits
supernova cosmology data by Riess et al. From another side, in this case every
massive body, slowly moving relatively to the background, would experience a
constant acceleration, proportional to the Hubble constant, of the same order
as a small additional acceleration of Pioneer 10, 11.Comment: 5 pages. It was presented: at SIGRAV'2000 Congress, Italy (this
version); in Proc. of the Int. Symp. "FFP 4" (9-13 Dec 2000, Hyderabad,
India), Sidharth& Altaisky, Eds., Kluwer Academic/Plenum, 2001;in Proc. of
the 4th Edoardo Amaldi Conference on GW (Perth, W. Australia, 8-13 July 2001
Coulomb effects in a ballistic one-channel S-S-S device
We develop a theory of Coulomb oscillations in superconducting devices in the
limit of small charging energy . We consider a small
superconducting grain of finite capacity connected to two superconducting leads
by nearly ballistic single-channel quantum point contacts. The temperature is
supposed to be very low, so there are no single-particle excitations on the
grain. Then the behavior of the system may be described as quantum mechanics of
the superconducting phase on the island. The Josephson energy as a function of
this phase has two minima which become degenerate at the phase difference on
the leads equal to , the tunneling amplitude between them being controlled
by the gate voltage at the grain. We find the Josephson current and its
low-frequency fluctuations and predict their periodic dependence on the induced
charge with period .Comment: 11 pages, REVTeX, 10 figures, uses eps
On the polarization properties of the charmed baryon Lambda^+_c in the Lambda^+_c -> p + K^- + pi^+ + pi^0 decay
The polarization properties of the charmed Lambda^+_c baryon are investigated
in weak non-leptonic four-body Lambda^+_c -> p + K^- + pi^+ + pi^0 decay. The
probability of this decay and the angular distribution of the probability are
calculated in the effective quark model with chiral U(3)XU(3) symmetry
incorporating Heavy Quark Effective theory (HQET) and the extended
Nambu-Jona-Lasinio model with a linear realization of chiral U(3)XU(3)
symmetry. The theoretical value of the probability of the decay Lambda^+_c -> p
+ K^- + pi^+ + pi^0 relative to the probability of the decay Lambda^+_c -> p +
K^- + pi^+ does not contain free parameters and fits well experimental data.
The application of the obtained results to the analysis of the polarization of
the Lambda^+_c produced in the processes of photo and hadroproduction is
discussed.Comment: 10 pages, no figures, Late
Ignition of Deflagration and Detonation Ahead of the Flame due to Radiative Preheating of Suspended Micro Particles
We study a flame propagating in the gaseous combustible mixture with
suspended inert particles. The gas is assumed to be transparent for the
radiation emitted by the combustion products, while particles absorb and
re-emit the radiation. Thermal radiation heats the particles, which in turn
transfer the heat to the surrounding gaseous mixture by means of heat
conduction, so that the gas temperature lags that of the particles. We consider
different scenarios depending on the spatial distribution of the particles,
their size and the number density. In the case of uniform distribution of the
particles the radiation causes a modest increase of the temperature ahead of
the flame and the corresponding increase of the flame velocity. The effects of
radiation preheating is stronger for a flame with smaller normal velocity. In
the case of non-uniform distribution of the particles, such that the particles
number density is smaller just ahead of the flame and increases in the distant
region ahead of the flame, the preheating caused by the thermal radiation may
trigger additional independent source of ignition. This scenario requires the
formation of a temperature gradient with the maximum temperature sufficient for
ignition in the region of denser particles cloud ahead of the advancing flame.
Depending on the steepness of the temperature gradient formed in the unburned
mixture, either deflagration or detonation can be initiated via the Zeldovich's
gradient mechanism. The ignition and the resulting combustion regimes depend on
the temperature profile which is formed in effect of radiation absorption and
gas-dynamic expansion. In the case of coal dust flames propagating through a
layered dust cloud the effect of radiation heat transfer can result in the
propagation of combustion wave with velocity up to 1000m/s and can be a
plausible explanation of the origin of dust explosion in coal mines.Comment: 45 pages, 14 figures. Accepted for publication Combustion and Flame
29 June 201
Correlations of the local density of states in quasi-one-dimensional wires
We report a calculation of the correlation function of the local density of
states in a disordered quasi-one-dimensional wire in the unitary symmetry class
at a small energy difference. Using an expression from the supersymmetric
sigma-model, we obtain the full dependence of the two-point correlation
function on the distance between the points. In the limit of zero energy
difference, our calculation reproduces the statistics of a single localized
wave function. At logarithmically large distances of the order of the Mott
scale, we obtain a reentrant behavior similar to that in strictly
one-dimensional chains.Comment: Published version. Minor technical and notational improvements. 16
pages, 1 figur
Dielectric response of Anderson and pseudogapped insulators
Using a combination of analytic and numerical methods, we study the
polarizability of a (non-interacting) Anderson insulator in one, two, and three
dimensions and demonstrate that, in a wide range of parameters, it scales
proportionally to the square of the localization length, contrary to earlier
claims based on the effective-medium approximation. We further analyze the
effect of electron-electron interactions on the dielectric constant in
quasi-1D, quasi-2D and 3D materials with large localization length, including
both Coulomb repulsion and phonon-mediated attraction. The phonon-mediated
attraction (in the pseudogapped state on the insulating side of the
Superconductor-Insulator Transition) produces a correction to the dielectric
constant, which may be detected from a linear response of a dielectric constant
to an external magnetic field.Comment: 9 page
Electroproduction of Soft Pions at Large Momentum Transfers
We consider pion electroproduction on a proton target close to threshold for
Q^2 in the region 1-10 GeV^2. The momentum transfer dependence of the S-wave
multipoles at threshold, E_{0+} and L_{0+}, is calculated using light-cone sum
rules.Comment: 8 pages, 3 figures; Invited talk at the workshop on Exclusive
Reactions at High Momentum Transfer, 21-24 May 2007, Newport News, Virginia,
U.S.A. and International Conference on hadron Physics TROIA'07, 30 Aug. - 3
Sept. 2007, Canakkale, Turke
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