467 research outputs found
Contribution of hadronic light-by-light scattering to the hyperfine structure of muonium
The contribution of hadronic scattering of light-by-light to the hyperfine
structure of muonium is calculated using experimental data on the transition
form factors of two photons into a hadron. The amplitudes of interaction
between a muon and an electron with horizontal and vertical exchange are
constructed. The contributions due to the exchange of pseudoscalar, axial
vector, scalar and tensor mesons are taken into account.Comment: 13 pages, 1 figur
Sum of Lyapunov exponents of the Hodge bundle with respect to the Teichmuller geodesic flow
We compute the sum of the positive Lyapunov exponents of the Hodge bundle
with respect to the Teichmuller geodesic flow. The computation is based on the
analytic Riemann-Roch Theorem and uses a comparison of determinants of flat and
hyperbolic Laplacians when the underlying Riemann surface degenerates.Comment: Minor corrections. To appear in Publications mathematiques de l'IHE
Energy levels of mesonic helium in quantum electrodynamics
On the basis of variational method we study energy levels of pionic helium
and kaonic helium with an electron in ground state and
a meson in excited state with principal and orbital quantum numbers . Variational wave functions are taken in the Gaussian form. Matrix
elements of the basic Hamiltonian and corrections to vacuum polarization and
relativism are calculated analytically in a closed form. We calculate some
bound state energies and transition frequencies which can be studied in the
experiment.Comment: 12 pages, 6 figure
Numerical simulation system for parallel computing
Abstract. Mathematic modeling is used in many field
Square-tiled cyclic covers
A cyclic cover of the complex projective line branched at four appropriate
points has a natural structure of a square-tiled surface. We describe the
combinatorics of such a square-tiled surface, the geometry of the corresponding
Teichm\"uller curve, and compute the Lyapunov exponents of the determinant
bundle over the Teichm\"uller curve with respect to the geodesic flow. This
paper includes a new example (announced by G. Forni and C. Matheus in
\cite{Forni:Matheus}) of a Teichm\"uller curve of a square-tiled cyclic cover
in a stratum of Abelian differentials in genus four with a maximally degenerate
Kontsevich--Zorich spectrum (the only known example found previously by Forni
in genus three also corresponds to a square-tiled cyclic cover
\cite{ForniSurvey}).
We present several new examples of Teichm\"uller curves in strata of
holomorphic and meromorphic quadratic differentials with maximally degenerate
Kontsevich--Zorich spectrum. Presumably, these examples cover all possible
Teichm\"uller curves with maximally degenerate spectrum. We prove that this is
indeed the case within the class of square-tiled cyclic covers.Comment: 34 pages, 6 figures. Final version incorporating referees comments.
In particular, a gap in the previous version was corrected. This file uses
the journal's class file (jmd.cls), so that it is very similar to published
versio
Circadian Organization in Hemimetabolous Insects
The circadian system of hemimetabolous insects is reviewed in respect to the locus of the circadian clock and multioscillatory organization. Because of relatively easy access to the nervous system, the neuronal organization of the clock system in hemimetabolous insects has been studied, yielding identification of the compound eye as the major photoreceptor for entrainment and the optic lobe for the circadian clock locus. The clock site within the optic lobe is inconsistent among reported species; in cockroaches the lobula was previously thought to be a most likely clock locus but accessory medulla is recently stressed to be a clock center, while more distal part of the optic lobe including the lamina and the outer medulla area for the cricket. Identification of the clock cells needs further critical studies. Although each optic lobe clock seems functionally identical, in respect to photic entrainment and generation of the rhythm, the bilaterally paired clocks form a functional unit. They interact to produce a stable time structure within individual insects by exchanging photic and temporal information through neural pathways, in which
serotonin and pigment-dispersing factor (PDF) are involved as chemical messengers. The mutual interaction also plays an important role in seasonal adaptation of the rhythm
Fluid channels of upward deep solutions migration in dense carbonate rocks of Bashkirian stage
Fluid dynamic channels of deep solutions upward migration in dense carbonates of the Bashkirian stage oil reservoirs have been investigated. The morphological features of the structure of channels penetrating dense carbonate rocks have been reviewed. In all cases the fluid dynamic channels in limestone have a central cylindrical bore, from which rare side branches run. The communicating cavities are observed around the channels. The hollows of channels and cavities surrounding them are partially or completely healed with authigenous calcite doped with dolomite. Nature and sequence of structure transformations of fluid dynamic channels voids are due to changes in the composition of fluids under the influence of the oxidation products of hydrocarbons. There are two development stages of the channels: 1) formation of cylindrical channel on account of the processes of carbonate rocks dissolution; 2) mudding (healing) of channels' voids with authigenous calcite. Adjusted fluid dynamic channels in dense rocks provide the possibility of vertical flow for water-oil fluids during the formation of oil deposits
Inverse problem by Cauchy data on arbitrary subboundary for system of elliptic equations
We consider an inverse problem of determining coefficient matrices in an
-system of second-order elliptic equations in a bounded two dimensional
domain by a set of Cauchy data on arbitrary subboundary. The main result of the
article is as follows: If two systems of elliptic operators generate the same
set of partial Cauchy data on an arbitrary subboundary, then the coefficient
matrices of the first-order and zero-order terms satisfy the prescribed system
of first-order partial differential equations. The main result implies the
uniqueness of any two coefficient matrices provided that the one remaining
matrix among the three coefficient matrices is known
Statistical properties of spectral fluctuations for a quantum system with infinitely many components
Extending the idea formulated in Makino {\it{et al}}[Phys.Rev.E
{\bf{67}},066205], that is based on the Berry--Robnik approach [M.V. Berry and
M. Robnik, J. Phys. A {\bf{17}}, 2413], we investigate the statistical
properties of a two-point spectral correlation for a classically integrable
quantum system. The eigenenergy sequence of this system is regarded as a
superposition of infinitely many independent components in the semiclassical
limit. We derive the level number variance (LNV) in the limit of infinitely
many components and discuss its deviations from Poisson statistics. The slope
of the limiting LNV is found to be larger than that of Poisson statistics when
the individual components have a certain accumulation. This property agrees
with the result from the semiclassical periodic-orbit theory that is applied to
a system with degenerate torus actions[D. Biswas, M.Azam,and S.V.Lawande, Phys.
Rev. A {\bf 43}, 5694].Comment: 6 figures, 10 page
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