arXiv subjects
Publications and source records attributed to V. I. Shevchenko.
The leading perturbative contributions into the two-point gauge-invariant correlator $Tr $ are calculated at the one-loop order. It is shown, that nonlocal condensate is nonzero at this order. The relation with the renormalization properties of Wilson loops is discussed.
The cancellation of perturbative contributions to the string tension in gluodynamics in the framework of vacuum field correlators method is shown at the order $O(g^4)$ by explicit calculation. The general pattern of these cancellations at all orders and relation with the renormalization properties of the Wilson loop is discussed.
A fully nonlinear, time-asymptotic theory of resonant particle trapping in large-amplitude quasi-parallel Alfven waves is presented. The effect of trapped particles on the nonlinear dynamics of quasi-stationary Alfvenic discontinuities and coherent Alfven waves is highly non-trivial and forces to a significant departure of the theory from the conventional DNLS and KNLS equation models. The virial theorem is used to determine the time-asymptotic distribution function.
A contour gauge of general type is analysed where 1-form (vector potential) is expressed as a contour integral of the 2-form (field strength) along an arbitrary contour $C$. For a special class of contours the gauge condition reduces to $k_μ(x) A_μ(x) = 0 $ where $k_μ(x)$ is a tangent vector to the contour $C$. A simple proof of the nonabelian Stokes theorem is given demonstrating the advantage of the gauge.
The nonlinear dynamics of collisionless Alfven trains, including resonant particle effects is studied using the kinetic nonlinear Schroedinger (KNLS) equation model. Numerical solutions of the KNLS reveal the dynamics of Alfven waves to be sensitive to the sense of polarization as well as the angle of propagation with respect to the ambient magnetic field. The combined effects of both wave nonlinearity and Landau damping result in the evolutionary formation of stationaryOA S- and arc-polarized directional and rotational discontinuities. These waveforms are freqently observed in the interplanetary plasma.
The light-cone Hamiltonian, incorporating the nonperturbative dynamics of the $q\bar q$ system connected by the string is solved numerically. The spectrum is shown to coincide with that of the center-of-mass Hamiltonian within the accuracy of computation, displaying the expected degeneracies of the string states, but an overall shift due to different treatment of Z-graphs is obtained. The nonperturbative wave functions are calculated directly from the light-cone Hamiltonian for the first time, thus allowing the explicit estimation of nonperturbative effects in the parton model language. In this way one obtains the string contribution to the parton distributions and in the formfactors and structure functions.
Exact relations between gauge-invariant vacuum correlators in QCD are derived. Derivatives of the correlators are expressed in terms of higher orders correlators. The behaviour of the correlators at large and small distances due to these relations is discussed.
The influence of various kinetic effects (e.g. Landau damping, diffusive and collisional dissipation, and finite Larmor radius terms) on the nonlinear evolution of finite amplitude Alfvenic wave trains in a finite-beta environment is systematically investigated using a novel, kinetic nonlinear Schrodinger (KNLS) equation. The dynamics of Alfven waves is sensitive to the sense of polarization as well as the angle of propagation with respect to the ambient magnetic field. Numerical solution for the case with Landau damping reveals the formation of dissipative structures, which are quasi-stationary, S-polarized directional (and rotational) discontinuities which self-organize from parallel propagating, linearly polarized waves. Parallel propagating circularly polarized packets evolve to a few circularly polarized Alfven harmonics on large scales. Stationary arc-polarized rotational discontinuities form from obliquely propagating waves. Collisional dissipation, even if weak, introduces enhanced wave damping when beta is very close to unity. Cyclotron motion effects on resonant particle interactions introduce cyclotron resonance into the nonlinear Alfven wave dynamics.
Starting from the gauge-invariant quark-antiquark Green function the expression for the nonrelativistic meson scattering amplitude is obtained and the nonperturbative form of this amplitude is discussed.
The potentialities of the production of the scalar $K\bar K$ molecules in the $ϕ$ radiative decays are considered beyond the narrow resonance width approximation. It is shown that $BR(ϕ\rightarrowγf_0(a_0)\rightarrowγππ(πη))\approx (1÷2)\times 10^{-5}\ ,\BR(ϕ\rightarrowγ(f_0+a_0)\rightarrowγK^+K^-)\alt 10^{-6}$ and $BR(ϕ\rightarrowγ(f_0+a_0) \to γK^0\bar K^0)\alt 10^{-8}$. The mass spectra in the $ππ ,\ πη ,\ K^+K^-\ ,\ K^0\bar K^0$ channels are calculated. The imaginary part of the amplitude $ϕ\rightarrowγf_0(a_0)$ is calculated analytically. It is obtained the phase of the scalar resonance production amplitude that causes the interference patterns in the reaction $e^+e^-\rightarrowγπ^+π^-$ in the $ϕ$ meson mass region.