6,380 research outputs found
Exclusive charm production in pbar p collisions at s^1/2 <15 GeV
We discuss the open charm production in peripheral reactions
and , where
and stand for and
, respectively, at GeV, which corresponds to the
energy range of FAIR. Our consideration is based on the topological
decomposition of the planar quark and diquark diagrams which allows to estimate
consistently meson and baryon exchange trajectories and energy scale parameters
as well. The spin dependence is determined by the effective interaction of
lowest exchanged resonance. Unknown parameters are fixed by an independent
analysis of open strangeness production in and reactions and of SU(4) symmetry. We present the corresponding cross
sections and longitudinal double-spin asymmetries for exclusive binary
reactions with open charm mesons and baryons in the final state. The
polarization observables have a non-trivial and dependence which is
sensitive to details of the open charm production mechanism.Comment: 26 pages, 18 figure
Plasmonic shock waves and solitons in a nanoring
We apply the hydrodynamic theory of electron liquid to demonstrate that a
circularly polarized radiation induces the diamagnetic, helicity-sensitive dc
current in a ballistic nanoring. This current is dramatically enhanced in the
vicinity of plasmonic resonances. The resulting magnetic moment of the nanoring
represents a giant increase of the inverse Faraday effect. With increasing
radiation intensity, linear plasmonic excitations evolve into the strongly
non-linear plasma shock waves. These excitations produce a series of the well
resolved peaks at the THz frequencies. We demonstrate that the plasmonic wave
dispersion transforms the shock waves into solitons. The predicted effects
should enable multiple applications in a wide frequency range (from the
microwave to terahertz band) using optically controlled ultra low loss
electric, photonic and magnetic devices.Comment: 13 pages, 12 figure
Spin filters with Fano dots
We compute the zero bias conductance of electrons through a single ballistic
channel weakly coupled to a side quantum dot with Coulomb interaction. In
contrast to the standard setup which is designed to measure the transport
through the dot, the channel conductance reveals Coulomb blockade dips rather
then peaks due to the Fano-like backscattering. At zero temperature the Kondo
effect leads to the formation of broad valleys of small conductance
corresponding to an odd number of electrons on the dot. By applying a magnetic
field in the dot region we find two dips corresponding to a total suppression
in the conductance of spins up and down separated by an energy of the order of
the Coulomb interaction. This provides a possibility of a perfect spin filter.Comment: 5 pages, 4 figures, to be published in European Physical Journal
A Model for the Sources of the Slow Solar Wind
Models for the origin of the slow solar wind must account for two seemingly
contradictory observations: The slow wind has the composition of the closed
field corona, implying that it originates from the continuous opening and
closing of flux at the boundary between open and closed field. On the other
hand, the slow wind also has large angular width, up to ~ 60{\circ}, suggesting
that its source extends far from the open-closed boundary. We propose a model
that can explain both observations. The key idea is that the source of the slow
wind at the Sun is a network of narrow (possibly singular) open-field corridors
that map to a web of separatrices and quasi-separatrix layers in the
heliosphere. We compute analytically the topology of an open-field corridor and
show that it produces a quasi-separatrix layer in the heliosphere that extends
to angles far from the heliospheric current sheet. We then use an MHD code and
MDI/SOHO observations of the photospheric magnetic field to calculate
numerically, with high spatial resolution, the quasi-steady solar wind and
magnetic field for a time period preceding the August 1, 2008 total solar
eclipse. Our numerical results imply that, at least for this time period, a web
of separatrices (which we term an S-web) forms with sufficient density and
extent in the heliosphere to account for the observed properties of the slow
wind. We discuss the implications of our S-web model for the structure and
dynamics of the corona and heliosphere, and propose further tests of the model
Quantitative assessment of reentrainment in the electrocyclone
The paper was devoted to the investigation of the reentrainment which was a parasitic effect incipient at the gas-cleaning systems – cyclones. It was demonstrated that the reentrainment arises at the speed of the aerosol from 14 to 27 m/sec. The quantitative characteristics of the reentrainment were determined.The research project has been supported by Russian Foundation for Basic Research (grant 14–08–00046а)
Proton strangeness form factors in (4,1) clustering configurations
We reexamine a recent result within a nonrelativistic constituent quark model
(NRCQM) which maintains that the uuds\bar s component in the proton has its
uuds subsystem in P state, with its \bar s in S state (configuration I). When
the result are corrected, contrary to the previous result, we find that all the
empirical signs of the form factors data can be described by the lowest-lying
uuds\bar s configuration with \bar s in P state that has its uuds subsystem in
state (configuration II). Further, it is also found that the removal of the
center-of-mass (CM) motion of the clusters will enhance the contributions of
the transition current considerably. We also show that a reasonable description
of the existing form factors data can be obtained with a very small probability
P_{s\bar s}=0.025% for the uuds\bar s component. We further see that the
agreement of our prediction with the data for G_A^s at low-q^2 region can be
markedly improved by a small admixture of configuration I. It is also found
that by not removing CM motion, P_{s\bar s} would be overestimated by about a
factor of four in the case when transition dominates over direct currents.
Then, we also study the consequence of a recent estimate reached from analyzing
the existing data on quark distributions that P_{s\bar s} lies between 2.4-2.9%
which would lead to a large size for the five-quark (5q) system, as well as a
small bump in both G^s_E+\eta G^s_M and G^s_E in the region of q^2 =< 0.1
GeV^2.Comment: Prepared for The Fifth Asia-Pacific Conference on Few-Body Problems
in Physics 2011 in Seoul, South Korea, 22-26 August 201
Inclusive quasi-elastic electron-nucleus scattering
This article presents a review of the field of inclusive quasi-elastic
electron-nucleus scattering. It discusses the approach used to measure the data
and includes a compilation of data available in numerical form. The theoretical
approaches used to interpret the data are presented. A number of results
obtained from the comparison between experiment and calculation are then
reviewed. The analogies and differences to other fields of physics exploiting
quasi-elastic scattering from composite systems are pointed out.Comment: Accepted for publication in Reviews of Modern Physic
Configuration interaction calculation of hyperfine and P,T-odd constants on ^{207}PbO excited states for the electron EDM experiments
We report first configuration interaction calculations of hyperfine constants
A_\parallel and the effective electric field W_d acting on the electric dipole
moment of the electron, in two excited electronic states of ^{207}PbO. The
obtained hyperfine constants, A_\parallel = -3826 MHz for the a(1) state and
A_\parallel = 4887 MHz for the B(1) state, are in very good agreement with the
experimental data, -4113 MHz and 5000 \pm 200 MHz, respectively. We find W_d =
-(6.1 ^{+1.8}_{-0.6}) 10^{24} Hz/(e cm) for a(1), and W_d = (8.0 \pm 1.6)
10^{24} Hz/(e cm) for B(1). The obtained values are analyzed and compared to
recent relativistic coupled cluster results and a semiempirical estimate of W_d
for the a(1) state.Comment: 6 pages, REVTeX4 style, submitted to Pthys.Rev.
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