3,161 research outputs found
HYM-flation: Yang-Mills cosmology with Horndeski coupling
We propose new mechanism for inflation using classical SU(2) Yang-Mills (YM)
homogeneous and isotropic field non-minimally coupled to gravity via Horndeski
prescription. This is the unique generally and gauge covariant ghost-free YM
theory with the curvature-dependent action leading to second-order gravity and
Yang-Mills field equations. We show that its solution space contains de Sitter
boundary to which the trajectories are attracted for some finite time, ensuring
the robust inflation with a graceful exit. The theory can be generalized to
include the Higgs field leading to two-steps inflationary scenario, in which
the Planck-scale YM-generated inflation naturally prepares the desired initial
conditions for the GUT-scale Higgs inflation.Comment: 13 pages, 3 figure
Problems and strategy of the first flight to the comets
Substantiation is given for the urgency of using space equipment to study comets in order to work out the basic problem of the origin and evolution of the solar system. The potentialities and advantages of selecting ballistically-accessible objects among the newly discovered comets are shown (as a preliminary study). The technique of early detection of such objects is discussed
On the Question of Polygonality and Irregularities of the Shape of Certain Craters on the Moon
Evaluation of moon crater polygonality, and irregular shape
Effects of distance dependence of exciton hopping on the Davydov soliton
The Davydov model of energy transfer in molecular chains is reconsidered
assuming the distance dependence of the exciton hopping term. New equations of
motion for phonons and excitons are derived within the coherent state
approximation. Solving these nonlinear equations result in the existence of
Davydov-like solitons. In the case of a dilatational soliton, the amplitude and
width is decreased as a results of the mechanism introduced here and above a
critical coupling strength our equations do not allow for localized solutions.
For compressional solitons, stability is increased.Comment: RevTeX 13 pages, 3 Postscript figure
Penetrators (penetrating sondes) and new possibilities for study of the planets
The fields of possible use of penetrators in space research are considered. A survey of the condition of development and plans for use of penetrators abroad is presented and an analysis is given of the significance of scientific problems when probing planets
Directed current in the Holstein system
We propose a mechanism to rectify charge transport in the semiclassical
Holstein model. It is shown that localised initial conditions, associated with
a polaron solution, in conjunction with a nonreversion symmetric static
electron on-site potential constitute minimal prerequisites for the emergence
of a directed current in the underlying periodic lattice system. In particular,
we demonstrate that for unbiased spatially localised initial conditions,
violation of parity prevents the existence of pairs of counter-propagating
trajectories, thus allowing for a directed current despite the
time-reversibility of the equations of motion. Occurrence of long-range
coherent charge transport is demonstrated
Cubic spline prewavelets on the four-directional mesh
In this paper, we design differentiable, two dimensional, piecewise polynomial cubic prewavelets of particularly small compact support. They are given in closed form, and provide stable, orthogonal decompositions of L^2(\RR^2). In particular, the splines we use in our prewavelet constructions give rise to stable bases of spline spaces that contain all cubic polynomials, whereas the more familiar box spline constructions cannot reproduce all cubic polynomials, unless resorting to a box spline of higher polynomial degree
Braided Picard groups and graded extensions of braided tensor categories
We classify various types of graded extensions of a finite braided tensor category in terms of its -categorical Picard groups. In particular, we prove that braided extensions of by a finite group correspond to braided monoidal -functors from to the braided -categorical Picard group of (consisting of invertible central -module categories). Such functors can be expressed in terms of the Eilnberg-Mac~Lane cohomology. We describe in detail braided -categorical Picard groups of symmetric fusion categories and of pointed braided fusion categories
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