117764895
Physical constants and invariant charges of the U(1) x SU(3) model
125323640
{QCD} Sum Rule Analysis of the Pion Form-factor Behavior in Small $Q^2$ Region
118213659
Pion form factor in a scalar model
SummaryUsing as an example the simple scalar modelρ(6)3; we describe our method of analysing the bound-state form factors based on the systematic use of the alpha-representation for Feynman diagrams. The nature of «nonrenormalization group» logarithms specific for the form-factor-type problems is investigated. The summation of ladder contributions is performed in the leading-logarithm approximation.RiassuntoUsando come esempio il semplice modello scalareρ(6)3 si descrive il metodo di analizzare i fattori di forma dello stato legato basati sull’uso sistematico della rappresentazione alfa per i diagrammi di Feyman. Si studia la natura dei logaritmi del gruppo di non rinormalizzazione specifico di problemi di tipo fattore di forma. Si esegue la somma dei contributi di a gradini nell’approssimazione del logaritmo principale.РезюмеНа примере простой скалярной моделиρ(6)3 излагается метод анализа формфакторов составных систем, основанный на систематическом использовании альфа-представления фейнмановских диаграмм. Исследуется природа «неренормгрупповых» логарифмов, специфичных для задач формфакторного типа. Проведено суммирование лестничных вкладов в главном лограрифмическом приближении.
120050425
KAON ELECTROMAGNETIC RADIUS
We obtain a QCD sum rule for the kaon form factor at small Q2. It determines, with a rather good accuracy, the kaon charge radius which is in agreement with the experimental value. We also discuss a sum rule for the difference .
120836438
Quantum gravitational effects in an isotropic universe
Effects of vacuum polarization by an external gravitational field in a system of spinor, scalar, and massive vector particles are considered in the model of conformally flat space-time. Expressions are obtained for the radiative corrections, and the part they play in gravitational theory is analyzed in the limits of weak (Vertical BarR/sup k//sub i/Vertical Bar m/sup 2/) gravitational fields. The Appendix gives expressions for the rate of spontaneous production of real particles by a strong gravitational field and the energy-momentum tensor of real particles in the ultrarelativistic limit; a law of increase of the entropy of an ultrarelativistic medium is also formulated.
120815334
Local Quark - Hadron Duality and Nucleon Form-factors in {QCD}
Abstract Quark-hadron duality is incorporated to estimate the non-perturbative O(α 0 S -contribution to the nucleon form factors G N E,M ( t ). For 1 t 2 the results are in satisfactory agreement with the existing data. This means that the observed dipole behaviour of G N ( t ) has nothing to do with the short distance dynamics.
2691762
Dynamics of relativistic particles with Lagrangians dependent on acceleration
Models of relativistic particles with Lagrangians L(k1), depending on the curvature of the worldline k1, are considered. By making use of the Frenet basis, the equations of motion are reformulated in terms of the principal curvatures of the worldline. It is shown that for arbitrary Lagrangian function L(k1) these equations are completely integrable, i.e., the principal curvatures are defined by integrals. The constants of integration are the particle mass and its spin. The developed method is applied to the study of a model of a relativistic particle with maximal proper acceleration, whose Lagrangian is uniquely determined by a modified form of the invariant relativistic interval. This model gives us an example of a consistent relativistic dynamics obeying the principle of a superiorly limited value of the acceleration, advanced recently.
124960100
DECONFINEMENT OF QUARKS IN THE NAMBU-GOTO STRING WITH MASSIVE ENDS
122614461
A nonlinear two-dimensional sigma-model in relativistic string theory
It is shown in what way the nonlinear two-dimensional SO(1, 2)/SO(1, 1)-sigma model appears in the theory of a relativistic string moving in three-dimensional space-time.
1154510
Casimir energy of a compact cylinder under the condition epsilon mu = c**(-2)
Abstract The Casimir energy of an inﬁnite compact cylinder placed in a uniform un-bounded medium is investigated under the continuity condition for the lightvelocity when crossing the interface. As a characteristic parameter in theproblem the ratio ξ 2 = (e 1 − e 2 ) 2 /(e 1 + e 2 ) 2 = (µ 1 − µ 2 ) 2 /(µ 1 + µ 2 ) 2 ≤ 1is used, where e 1 and µ 1 are, respectively, the permittivity and permeabilityof the material making up the cylinder and e 2 and µ 2 are those for the sur-rounding medium. It is shown that the expansion of the Casimir energy inpowers of this parameter begins with the term proportional to ξ 4 . The ex-plicit formulas permitting us to ﬁnd numerically the Casimir energy for anyﬁxed value of ξ 2 are obtained. Unlike a compact ball with the same propertiesof the materials, the Casimir forces in the problem under consideration areattractive. The implication of the calculated Casimir energy in the ﬂux tubemodel of conﬁnement is brieﬂy discussed.12.20.Ds, 03.70.+k, 12.40.-y Typeset using REVTEX
93177597
Differential Geometry and Nonlinear Field Models