Mesons as qbar-q Bound States from Euclidean 2-Point Correlators in the Bethe-Salpeter Approach

We investigate the 2-point correlation function for the vector current. The gluons provide dressings for both the quark self energy as well as the vector vertex function, which are described consistently by the rainbow Dyson-Schwinger equation and the inhomogeneous ladder Bethe-Salpeter equation. The form of the gluon propagator at low momenta is modeled by a 2-parameter ansatz fitting the weak pion decay constant. The quarks are confined in the sense that the quark propagator does not have a pole at timelike momenta. We determine the ground state mass in the vector channel from the Euclidean time Fourier transform of the correlator, which has an exponential falloff at large times. The ground state mass lies around 590 MeV and is almost independent of the model form for the gluon propagator. This method allows us to stay in Euclidean space and to avoid analytic continuation of the quark or gluon propagators into the timelike region.Comment: 21 pages (REVTEX), 8 Postscript figure

On the energy leakage of discrete wavelet transform

The energy leakage is an inherent deficiency of discrete wavelet transform (DWT) which is often ignored by researchers and practitioners. In this paper, a systematic investigation into the energy leakage is reported. The DWT is briefly introduced first, and then the energy leakage phenomenon is described using a numerical example as an illustration and its effect on the DWT results is discussed. Focusing on the Daubechies wavelet functions, the band overlap between the quadrature mirror analysis filters was studied and the results reveal that there is an unavoidable tradeoff between the band overlap degree and the time resolution for the DWT. The dependency of the energy leakage to the wavelet function order was studied by using a criterion defined to evaluate the severity of the energy leakage. In addition, a method based on resampling technique was proposed to relieve the effects of the energy leakage. The effectiveness of the proposed method has been validated by numerical simulation study and experimental study

Методы анализа микроальтернации ЭКГ-сигнала

The paper presents the methods of analysis of the ECG-signal alternations, which are increasingly being used in everyday clinical practice. Evaluation of these indicators is an important component of the analysis of myocardial electrical instability and the development of potentially dangerous arrhythmias. New technologies of reception and analysis of the electric field of the heart reflect the creation of a new generation of functional diagnostic methods. Now the method of dispersion mapping is increasingly being used for the screening in Russia.В работе представлены используемые методы анализа альтернаций ЭКГ-сигнала, которые все шире используются в повседневной клинической практике. Оценка данных показателей является важной составляющей анализа электрической нестабильности миокарда и развития потенциально-опасных аритмий. Новые технологии получения и анализа электрического поля сердца отражают создание нового поколения методов функциональной диагностики. Метод дисперсионного картирования находит все большее применение в РФ в настоящее время для проведения скрининга

Успехи клинического применения метода дисперсионного картирования

The article includes a brief description of the new method in the electrocardiographic diagnostics — Dispersion Mapping, and the main results of clinical studies. The method finds now the increasing application in clinical practice. The general theoretical prerequisites and methodological aspects of application of the method were considered and the basic principles of analysis were proposed. The results of our original studies were stated. The data on diagnostic and prognostic meaning of the dispersion mapping in health groups and group of patients with different forms of the Coronary Heart Disease were heavily emphasized. Some distant outcomes of the acute coronary syndrome and results of other recent clinical studies were considered.Статья содержит краткое описание нового метода электрокардиографической диагностики — дисперсионного картирования и основные результаты клинических исследований. Метод находит в настоящее время все большее применение в клинической практике. Рассмотрены общие теоретические предпосылки и методические аспекты использования метода, представлены основные принципы анализа. Изложены результаты собственных оригинальных исследований. Значительное внимание уделено данным о диагностическом и прогностическом значении метода дисперсионного картирования в группах здоровых лиц и больных различными формами ИБС. Рассмотрены отдаленные исходы острого коронарного синдрома и другие результаты клинических исследований, выполненных на протяжении последних лет

Дисперсионное картирование в донозологической диагностике

Dispersion mapping in donozologic diagnostic

Solutions of the Strominger System via Stable Bundles on Calabi-Yau Threefolds

We prove that a given Calabi-Yau threefold with a stable holomorphic vector bundle can be perturbed to a solution of the Strominger system provided that the second Chern class of the vector bundle is equal to the second Chern class of the tangent bundle. If the Calabi-Yau threefold has strict SU(3) holonomy then the equations of motion derived from the heterotic string effective action are also satisfied by the solutions we obtain.Comment: 19 pages, late

Subprocess Size in Hard Exclusive Scattering

The interaction region of hard exclusive hadron scattering can have a large transverse size due to endpoint contributions, where one parton carries most of the hadron momentum. The endpoint region is enhanced and can dominate in processes involving multiple scattering and quark helicity flip. The endpoint Fock states have perturbatively short lifetimes and scatter softly in the target. We give plausible arguments that endpoint contributions can explain the apparent absence of color transparency in fixed angle exclusive scattering and the dimensional scaling of transverse rho photoproduction at high momentum transfer, which requires quark helicity flip. We also present a quantitative estimate of Sudakov effects.Comment: 16 pages, 4 figures, JHEP style; v2: quantitative estimate of Sudakov effects and more detailed discussion of endpoint behaviour of meson distribution amplitude added, few other clarifications, version to appear in Phys. Rev.

Electroproduction of Charmonia off Nuclei

In a recent publication we have calculated elastic charmonium production in ep collisions employing realistic charmonia wave functions and dipole cross sections and have found good agreement with the data in a wide range of s and Q^2. Using the ingredients from those calculations we calculate exclusive electroproduction of charmonia off nuclei. Here new effects become important, (i) color filtering of the c-cbar pair on its trajectory through nuclear matter, (ii) dependence on the finite lifetime of the c-cbar fluctuation (coherence length) and (iii) gluon shadowing in a nucleus compared to the one in a nucleon. Total coherent and incoherent cross sections for C, Cu and Pb as functions of s and Q^2 are presented together with some differential cross sections. The results can be tested with future electron-nucleus colliders or in peripheral collisions of ultrarelativistic heavy ions.Comment: 21 pages of Latex including 14 figures; few misprints are fixe

Monopoles and clusters

We define and study certain hyperkaehler manifolds which capture the asymptotic behaviour of the SU(2)-monopole metric in regions where monopoles break down into monopoles of lower charges. The rate at which these new metrics approximate the monopole metric is exponential, as for the Gibbons-Manton metric.Comment: v2.: relation to calorons mentioned; added explanation

Quasiparticle scattering and local density of states in the d-density wave phase

We study the effects of single-impurity scattering on the local density of states in the high-$T_c$ cuprates. We compare the quasiparticle interference patterns in three different ordered states: d-wave superconductor (DSC), d-density wave (DDW), and coexisting DSC and DDW (DSC-DDW). In the coexisting state, at energies below the DSC gap, the patterns are almost identical to those in the pure DSC state with the same DSC gap. However, they are significantly different for energies greater than or equal to the DSC gap. This transition at an energy around the DSC gap can be used to test the nature of the superconducting state of the underdoped cuprates by scanning tunneling microscopy. Furthermore, we note that in the DDW state the effect of the coherence factors is stronger than in the DSC state. The new features arising due to DDW ordering are discussed.Comment: 6 page, 5 figures (Higher resolution figures are available by request