38,208 research outputs found
Topological Structure of the Vacuum, Cosmological Constant and Dark Energy
In this review we present a theory of cosmological constant and Dark Energy
(DE), based on the topological structure of the vacuum. The Multiple Point
Principle (MPP) is reviewed. It demonstrates the existence of the two vacua
into the SM. The Froggatt-Nielsen's prediction of the top-quark and Higgs
masses is given in the assumption that there exist two degenerate vacua in the
SM. This prediction was improved by the next order calculations. We also
considered B.G. Sidharth's theory of cosmological constant based on the
non-commutative geometry of the Planck scale space-time, what gives an
extremely small DE density providing the accelerating expansion of the
Universe. Theory of two degenerate vacua - the Planck scale phase and
Electroweak (EW) phase - also is reviewed, topological defects in these vacua
are investigated, also the Compton wavelength phase suggested by B.G. Sidharth
was discussed. A general theory of the phase transition and the problem of the
vacuum stability in the SM is reviewed. Assuming that the recently discovered
at the LHC new resonance with mass GeV is a new scalar
bound state , earlier predicted by C.D. Froggatt, H.B. Nielsen
and L.V. Laperashvili, we try to provide the vacuum stability in the SM and
exact accuracy of the MPP.Comment: 37 pages and 7 figures. arXiv admin note: text overlap with
arXiv:1601.03231; text overlap with arXiv:1302.2716 by other author
Incorporating Radial Flow in the Lattice Gas Model for Nuclear Disassembly
We consider extensions of the lattice gas model to incorporate radial flow.
Experimental data are used to set the magnitude of radial flow. This flow is
then included in the Lattice Gas Model in a microcanonical formalism. For
magnitudes of flow seen in experiments, the main effect of the flow on
observables is a shift along the axis.Comment: Version accepted for publication in Phys. Rev. C, Rapid Communicatio
Universal Low-Energy Dynamics for Rotating Black Holes
Fundamental string theory has been used to show that low energy excitations
of certain black holes are described by a two dimensional conformal field
theory. This picture has been found to be extremely robust. In this paper it is
argued that many essential features of the low energy effective theory can be
inferred directly from a semiclassical analysis of the general Kerr-Newman
solution of supersymmetric four-dimensional Einstein-Maxwell gravity, without
using string theory. We consider the absorption and emission of scalars with
orbital angular momentum, which provide a sensitive probe of the black hole. We
find that the semiclassical emission rates -including superradiant emission and
greybody factors - for such scalars agree in striking detail with those
computed in the effective conformal field theory, in both four and five
dimensions. Also the value of the quantum mass gap to the lowest-lying
excitation of a charge- black hole, in Planck units, can be
derived without knowledge of fundamental string theory.Comment: 24 pages, no figures. Typos corrected, some comments adde
Vortex Washboard Voltage Noise in Type-II Superconductors
In order to characterize flux flow through disordered type-II
superconductors, we investigate the effects of columnar and point defects on
the vortex velocity / voltage power spectrum in the driven non-equilibrium
steady state. We employ three-dimensional Metropolis Monte Carlo simulations to
measure relevant physical observables including the force-velocity /
current-voltage (I-V) characteristics, vortex spatial arrangement and structure
factor, and mean flux line radius of gyration. Our simulation results compare
well to earlier findings and physical intuition. We focus specifically on the
voltage noise power spectra in conjunction with the vortex structure factor in
the presence of weak columnar and point pinning centers. We investigate the
vortex washboard noise peak and associated higher harmonics, and show that the
intensity ratios of the washboard harmonics are determined by the strength of
the material defects rather than the type of pins present. Through varying
columnar defect lengths and pinning strengths as well as magnetic flux density
we further explore the effect of the material defects on vortex transport. It
is demonstrated that the radius of gyration displays quantitatively unique
features that depend characteristically on the type of material defects present
in the sample.Comment: Latex, 17 pages, 14 figure
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