Dynamical regimes of the QCD string with quarks
SummaryThis a short report on the first paper (A. Dubin, A. Kaidalov and Yu.  (1993)) of a series devoted to quantum dynamics of the quark-antiquark system at large distances. Starting from the QCD Lagrangian, we derive the effective action for a massive quark and antiquark at large distances, corresponding to the minimal-area law of the Wilson loop. The path integral method is used to quantize the system and the spectrum is obtained with asymptotically linear Regge trajectories. Two dynamical regimes distinguished by the string energy-momentum distribution are found: at large orbital excitations (l≫1) the system behaves as a string and yields the Regge slope of 1/2πσ, while at smalll one obtains a potential-like regime for the relativistic or non-relativistic system. The problem of relative time is clarified. It is shown that in the valence-quark approximation one can reduce the initial four-dimensional dynamics to three dimensions.

title: Spin-dependent interaction in the deconfined phase of QCD
abstract: Spin-dependent deconfined interaction in the Q ¯ Q system is derived from the field correlators known from lattice and analytic calculations. As a result hyperfine splitting is found numerically for charmonium, bottomonium and strangeonium in the range T c ≤ T ≤ 2T c. Spin-orbit interaction due to magnetic correlators (the Thomas term) is able to produce numerous Q ¯ Q bound states with accumulation point at M = m Q + m ¯ Q. Possible influence of these effects on the thermo-dynamics of quark-gluon plasma is discussed. In honor of A.Di Giacomo on his seventieth birthday.

title: Perturbative-nonperturbative interference in the static QCD interaction at small distances
abstract: Short distance static quark--antiquark interaction is studied systematically using the background perturbation theory with nonperturbative background described by field correlators. A universal linear term $\frac{6N_c\alpha_s\sigma r}{2\pi}$ is observed at small distance $r$ due to the interference between perturbative and nonperturbative contributions. Possible modifications of this term due to additional subleading terms are discussed and implications for systematic corrections to OPE are formulated.

title: The QCD vacuum , confinement and strings in the Vacuum Correlator Method
abstract: In this review paper the QCD vacuum properties and the structure of color fields in hadrons are studied using complete set of gauge-invariant correlators of the gluon fields. Confinement in QCD is produced by the correlators of some certain Lorentz structure, which violate abelian Bianchi identities and therefore are absent in the case of QED. These correlators are used to define an effective colorless field, which satisfies Maxwell equation with nonzero effective magnetic current. With the help of the effective field and correlators it is demonstrated that quarks are confined due to effective magnetic currents, squeezing gluonic fields into a string, in agreement with the " dual Meissner effect ". Distribution of effective gluonic fields are plotted in mesons, baryons and glueballs with static sources.

title: Field correlators in QCD. Theory and applications
abstract: This review is aimed to demonstrate the basics and use of formalism of gauge-invariant nonlocal correlators in nonabelian gauge theories. Many phenomenologically interesting nonperturbative aspects of gluodynamics and QCD can be described in terms of correlators of the nonabelian field strength tensors. It is explained how the properties of correlator ensemble encode the structure of QCD vacuum and determine different nonperturbative observables. It is argued that in gluodynamics and QCD the dominant role is played by the lowest nontrivial two-point correlator (Gaussian dominance). Lattice measurements of field correlators are discussed. Important for the formalism theoretical tools, such as nonabelian Stokes theorem, background perturbation theory, cluster expansion, as well as phenomenological applications to the heavy quarkonium dynamics and QCD phase transition are reviewed.

title: Rotating QCD string and the meson spectrum
abstract: The spectra of light-light and heavy-light mesons are described by spinless Salpeter equation and Dirac equation respectively, which predict linear dependence of the meson mass squared M^2 on angular momentum J and number of radial nodes n. Both spectra are computed by the WKB method and shown to agree with exact numerical data within few percent even for the lowest levels. The drawback of Salpeter and Dirac equation is that (inverse) Regge slopes do not coincide with the string ones, 2\pi\sigma and \pi\sigma respectively, because the string dynamics is not taken into account properly. The lacking string rotation is introduced via effective Hamiltonian derived from QCD which generates linear Regge trajectories for light mesons with the correct string slope.

title: Experimental study of gluon and sea quark polarizations (The first stage of the POLEX program at UNK)

title: Search for parity-nonconservation effects in deep-inelastic μ-N interaction
abstract: The difference of the cross sections for deep inelastic scattering of muons with average momenta 21 GeV/ c with right and left helicity at large angles, i.e., with large momentum transfer, has been measured. No statistically-significant dependence of cross sections on the longitudinal polarization of muons has been found, i.e. no parity-nonconservation effects in deep inelastic μN interaction have been observed. The magnitude of the cross-section asymmetry R = [〈σ R 〉 − 〈σ L 〉] [〈σ R 〉+ + 〈σ L 〉] may be represented as R = β 〈 Q 2 〉 = (− 4 ± 6) × 10 −3 〈 Q 2 , (GeV/ c ) 2 〉. The limitations G o ( μ ) = (+ 6 ± 10) G have been obtained for the constant G o ( μ ) of vector-axial interaction ( G o (μ) 2 ) [ μ γα(1 + γ 5 )μ] J α o (hadron, V-A).

title: Proportional Chamber Readout System

title: Electronic System of Data Output with Digital Processor for Multichannel Cherenkov Counter with Small Multipliers. (In Russian)

title: Memory matrixes with ferrite cores for wire spark chambers.