186 research outputs found
Deflection of coronal rays by remote CMEs: shock wave or magnetic pressure?
We analyze five events of the interaction of coronal mass ejections (CMEs)
with the remote coronal rays located up to 90^\circ away from the CME as
observed by the SOHO/LASCO C2 coronagraph. Using sequences of SOHO/LASCO C2
images, we estimate the kink propagation in the coronal rays during their
interaction with the corresponding CMEs ranging from 180 to 920 km/s within the
interval of radial distances form 3 R. to 6 R. . We conclude that all studied
events do not correspond to the expected pattern of shock wave propagation in
the corona. Coronal ray deflection can be interpreted as the influence of the
magnetic field of a moving flux rope related to a CME. The motion of a
large-scale flux rope away from the Sun creates changes in the structure of
surrounding field lines, which are similar to the kink propagation along
coronal rays. The retardation of the potential should be taken into account
since the flux rope moves at high speed comparable with the Alfven speed.Comment: Accepted for Publication in Solar Physic
Research of Gravitation in Flat Minkowski Space
In this paper it is introduced and studied an alternative theory of
gravitation in flat Minkowski space. Using an antisymmetric tensor, which is
analogous to the tensor of electromagnetic field, a non-linear connection is
introduced. It is very convenient for studying the perihelion/periastron shift,
deflection of the light rays near the Sun and the frame dragging together with
geodetic precession, i.e. effects where angles are involved. Although the
corresponding results are obtained in rather different way, they are the same
as in the General Relativity. The results about the barycenter of two bodies
are also the same as in the General Relativity. Comparing the derived equations
of motion for the -body problem with the Einstein-Infeld-Hoffmann equations,
it is found that they differ from the EIH equations by Lorentz invariant terms
of order .Comment: 28 page
THE TIGHT-BINDING APPROACH TO THE DIELECTRIC RESPONSE IN THE MULTIBAND SYSTEMS
Starting from the random phase approximation for the weakly coupled multiband
tightly-bounded electron systems, we calculate the dielectric matrix in terms
of intraband and interband transitions. The advantages of this representation
with respect to the usual plane-wave decomposition are pointed out. The
analysis becomes particularly transparent in the long wavelength limit, after
performing the multipole expansion of bare Coulomb matrix elements. For
illustration, the collective modes and the macroscopic dielectric function for
a general cubic lattice are derived. It is shown that the dielectric
instability in conducting narrow band systems proceeds by a common softening of
one transverse and one longitudinal mode. Furthermore, the self-polarization
corrections which appear in the macroscopic dielectric function for finite band
systems, are identified as a combined effect of intra-atomic exchange
interactions between electrons sitting in different orbitals and a finite
inter-atomic tunneling.Comment: 20 pages, LaTeX, no figure
High frequency sound in superfluid 3He-B
We present measurements of the absolute phase velocity of transverse and
longitudinal sound in superfluid 3He-B at low temperature, extending from the
imaginary squashing mode to near pair-breaking. Changes in the transverse phase
velocity near pair-breaking have been explained in terms of an order parameter
collective mode that arises from f-wave pairing interactions, the so-called
J=4- mode. Using these measurements, we establish lower bounds on the energy
gap in the B-phase. Measurement of attenuation of longitudinal sound at low
temperature and energies far above the pair-breaking threshold, are in
agreement with the lower bounds set on pair-breaking. Finally, we discuss our
estimations for the strength of the f-wave pairing interactions and the Fermi
liquid parameter, F4s.Comment: 15 pages, 8 figures, accepted to J. Low Temp. Phy
Thermal correction to the Casimir force, radiative heat transfer, and an experiment
The low-temperature asymptotic expressions for the Casimir interaction
between two real metals described by Leontovich surface impedance are obtained
in the framework of thermal quantum field theory. It is shown that the Casimir
entropy computed using the impedance of infrared optics vanishes in the limit
of zero temperature. By contrast, the Casimir entropy computed using the
impedance of the Drude model attains at zero temperature a positive value which
depends on the parameters of a system, i.e., the Nernst heat theorem is
violated. Thus, the impedance of infrared optics withstands the thermodynamic
test, whereas the impedance of the Drude model does not. We also perform a
phenomenological analysis of the thermal Casimir force and of the radiative
heat transfer through a vacuum gap between real metal plates. The
characterization of a metal by means of the Leontovich impedance of the Drude
model is shown to be inconsistent with experiment at separations of a few
hundred nanometers. A modification of the impedance of infrared optics is
suggested taking into account relaxation processes. The power of radiative heat
transfer predicted from this impedance is several times less than previous
predictions due to different contributions from the transverse electric
evanescent waves. The physical meaning of low frequencies in the Lifshitz
formula is discussed. It is concluded that new measurements of radiative heat
transfer are required to find out the adequate description of a metal in the
theory of electromagnetic fluctuations.Comment: 19 pages, 4 figures. svjour.cls is used, to appear in Eur. Phys. J.
Elastic double diffractive production of axial-vector \chi_c(1^{++}) mesons and the Landau-Yang theorem
We discuss exclusive elastic double diffractive axial-vector \chi_c(1^{+})
meson production in proton-antiproton collisions at the Tevatron. The amplitude
for the process is derived within the k_t-factorisation approach with
unintegrated gluon distribution functions (UGDFs). We show that the famous
Landau-Yang theorem is not applicable in the case of off-shell gluons.
Differential cross sections for different UGDFs are calculated. We compare
exclusive production of \chi_c(1^+) and \chi_c(0^+). The contribution of
\chi_c(1^+) to the J/\Psi + \gamma channel is smaller than that of the
\chi_c(0^+) decay, but not negligible and can be measured. The numerical value
of the ratio of the both contributions is almost independent of UGDFs modeling.Comment: 14 pages, 5 figures, a numerical error corrected, discussions
extended, conclusions unchange
On non-local variational problems with lack of compactness related to non-linear optics
We give a simple proof of existence of solutions of the dispersion manage-
ment and diffraction management equations for zero average dispersion,
respectively diffraction. These solutions are found as maximizers of non-linear
and non-local vari- ational problems which are invariant under a large
non-compact group. Our proof of existence of maximizer is rather direct and
avoids the use of Lions' concentration compactness argument or Ekeland's
variational principle.Comment: 30 page
Small BGK waves and nonlinear Landau damping
Consider 1D Vlasov-poisson system with a fixed ion background and periodic
condition on the space variable. First, we show that for general homogeneous
equilibria, within any small neighborhood in the Sobolev space W^{s,p}
(p>1,s<1+(1/p)) of the steady distribution function, there exist nontrivial
travelling wave solutions (BGK waves) with arbitrary minimal period and
traveling speed. This implies that nonlinear Landau damping is not true in
W^{s,p}(s<1+(1/p)) space for any homogeneous equilibria and any spatial period.
Indeed, in W^{s,p} (s<1+(1/p)) neighborhood of any homogeneous state, the long
time dynamics is very rich, including travelling BGK waves, unstable
homogeneous states and their possible invariant manifolds. Second, it is shown
that for homogeneous equilibria satisfying Penrose's linear stability
condition, there exist no nontrivial travelling BGK waves and unstable
homogeneous states in some W^{s,p} (p>1,s>1+(1/p)) neighborhood. Furthermore,
when p=2,we prove that there exist no nontrivial invariant structures in the
H^{s} (s>(3/2)) neighborhood of stable homogeneous states. These results
suggest the long time dynamics in the W^{s,p} (s>1+(1/p)) and particularly, in
the H^{s} (s>(3/2)) neighborhoods of a stable homogeneous state might be
relatively simple. We also demonstrate that linear damping holds for initial
perturbations in very rough spaces, for linearly stable homogeneous state. This
suggests that the contrasting dynamics in W^{s,p} spaces with the critical
power s=1+(1/p) is a trully nonlinear phenomena which can not be traced back to
the linear level
Two-body decays in the minimal 331 model
The two-body decays of the extra neutral boson Z_2 predicted by the minimal
331 model are analyzed. At the three-level it can decay into standard model
particles as well as exotic quarks and the new gauge bosons predicted by the
model. The decays into a lepton pair are strongly suppressed, with and . In the bosonic
sector, Z_2 would decay mainly into a pair of bilepton gauge bosons, with a
branching ratio below the 0.1 level. The Z_2 boson has thus a leptophobic and
bileptophobic nature and it would decay dominantly into quark pairs. The
anomaly-induced decays and , which occurs
at the one-loop level are studied. It is found that and at most. As for the and decays, with H a relatively light Higgs boson, they
are induced via Z'-Z mixing. It is obtained that
and . We also examine the flavor changing neutral
current decays and , which may have branching
fractions as large as and , respectively, and thus may be of
phenomenological interest.Comment: 14 pages, 3 figures, submitted to Physical Review
Resonance- and Chaos-Assisted Tunneling
We consider dynamical tunneling between two symmetry-related regular islands
that are separated in phase space by a chaotic sea. Such tunneling processes
are dominantly governed by nonlinear resonances, which induce a coupling
mechanism between ``regular'' quantum states within and ``chaotic'' states
outside the islands. By means of a random matrix ansatz for the chaotic part of
the Hamiltonian, one can show that the corresponding coupling matrix element
directly determines the level splitting between the symmetric and the
antisymmetric eigenstates of the pair of islands. We show in detail how this
matrix element can be expressed in terms of elementary classical quantities
that are associated with the resonance. The validity of this theory is
demonstrated with the kicked Harper model.Comment: 25 pages, 5 figure
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