877,879 research outputs found
Back reaction of vacuum and the renormalization group flow from the conformal fixed point
We consider the GUT-like model with two scalar fields which has infinitesimal
deviation from the conformal invariant fixed point at high energy region. In
this case the dominating quantum effect is the conformal trace anomaly and the
interaction between the anomaly-generated propagating conformal factor of the
metric and the usual dimensional scalar field. This interaction leads to the
renormalization group flow from the conformal point. In the supersymmetric
conformal invariant model such an effect produces a very weak violation of
sypersymmetry at lower energies.Comment: 15 pages, LaTex, ten figures, uuencoded fil
Analysis of the second order exchange self energy of a dense electron gas
We investigate the evaluation of the six-fold integral representation for the
second order exchange contribution to the self energy of a three dimensional
electron gas at the Fermi surface.Comment: 6 page
Quantization of bosonic fields with two mass and spin states
We investigate bosonic fields possessing two mass and spin states. The
density matrix in the first order formalism is obtained. The quantization of
fields in the first order formulation is performed and propagators are found.Comment: 9 page
Can the flyby anomaly be attributed to earth-bound dark matter?
We make preliminary estimates to assess whether the recently reported flyby
anomaly can be attributed to dark matter interactions. We consider both elastic
and exothermic inelastic scattering from dark matter constituents; for
isotropic dark matter velocity distributions, the former decrease, while the
latter increase, the final flyby velocity. The fact that the observed flyby
velocity anomaly shows examples with both positive and negative signs, requires
the dominance of different dark matter scattering processes along different
flyby trajectories. The magnitude of the observed anomalies requires dark
matter densities many orders of magnitude greater than the galactic halo
density. Such a large density could result from an accumulation cascade, in
which the solar system-bound dark matter density is much higher than the
galactic halo density, and the earth-bound density is much higher than the
solar system-bound density. We discuss a number of strong constraints on the
hypothesis of a dark matter explanation for the flyby anomaly. These require
dark matter to be non-self-annihilating, with the dark matter scattering cross
section on nucleons much larger, and the dark matter mass much lighter, than
usually assumed.Comment: Latex, 21 pages. v3: substantially revised and expanded; v4: version
to appear in Phys. Rev.
A Four-Dimensional Theory for Quantum Gravity with Conformal and Nonconformal Explicit Solutions
The most general version of a renormalizable theory corresponding to a
dimensionless higher-derivative scalar field model in curved spacetime is
explored. The classical action of the theory contains independent
functions, which are the generalized coupling constants of the theory. We
calculate the one-loop beta functions and then consider the conditions for
finiteness. The set of exact solutions of power type is proven to consist of
precisely three conformal and three nonconformal solutions, given by remarkably
simple (albeit nontrivial) functions that we obtain explicitly. The finiteness
of the conformal theory indicates the absence of a conformal anomaly in the
finite sector. The stability of the finite solutions is investigated and the
possibility of renormalization group flows is discussed as well as several
physical applications.Comment: LaTeX, 18 pages, no figure
On structure of effective action in four-dimensional quantum dilaton supergravity
A general structure of effective action in new chiral superfield model
associated with , supergravity is investigated. This model
corresponds to finite quantum field theory and does not demand the
regularization and renormalization at effective action calculation. It is shown
that in local approximation the effective action is defined by two objects
called general superfield effective lagrangian and chiral superfield effective
lagrangian. A proper-time method is generalized for calculation of these two
effective lagrangians in superfield manner. Power expansion of the effective
action in supercovariant derivatives is formulated and the lower terms of such
an expansion are calculated in explicit superfield form
Magnetopolaronic effects in electron transport through a single-level vibrating quantum dot
Magneto-polaronic effects are considered in electron transport through a
single-level vibrating quantum dot subjected to a transverse (to the current
flow) magnetic field. It is shown that the effects are most pronounced in the
regime of sequential electron tunneling, where a polaronic blockade of the
current at low temperatures and an anomalous temperature dependence of the
magnetoconductance are predicted. In contrast, for resonant tunneling of
polarons the peak conductance is not affected by the magnetic field.Comment: 7 pages, 2 figure
Nonequilibrium evolution thermodynamics
A new approach - nonequilibrium evolution thermodynamics, is compared with
classical variant of Landau approachComment: 4 pages, 1 figur
Correlated electronic structure, orbital-dependent correlations, and Lifshitz transition in tetragonal FeS
Using density functional plus dynamical mean-field theory method (DFT+DMFT)
with full self-consistency over the charge density, we study the effect of
electronic correlations on the electronic structure, magnetic properties,
orbital-dependent band renormalizations, and Fermi surface of the tetragonal
phase of bulk FeS. We perform a direct structural optimization of the
crystal structure of paramagnetic FeS, with respect to the lattice constant
and the internal coordinate of atom S. Our results show an
anomalous sensitivity of the electronic structure and magnetic properties of
FeS to fine details of its crystals structure. Upon expansion of the lattice
volume, we observe a remarkable change of the electronic structure of FeS which
is associated with a complete reconstruction of the Fermi surface topology
(Lifshitz transition). This behavior is ascribed to a correlation-induced shift
of the Van Hove singularity associated with the Fe orbitals at the
point across the Fermi level. The Lifshitz phase transition is accompanied by a
significant growth of local magnetic moments and emergence of strong
orbital-selective correlations. It is seen as a pronounced anomaly (`kink') in
the total energies upon expansion of the lattice, associated with a remarkable
enhancement of compressibility. This behavior is accompanied by an
orbital-dependent formation of local moments, a crossover from itinerant to
localized orbital-selective moment behavior of the Fe electrons. While
exhibiting weak effective mass enhancement of the Fe states , correlation effects reveal a strong impact on a position of the Van
Hove singularity at the point, implying a complex interplay between
electronic correlations and band structure effects in FeS
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