Evolution of the rotation of an artificial earth satellite under the influence of a perturbing moment which is constant in fixed axes

The change in the modulus of the vector of the kinetic moment of a satellite which is noted during the determination of the actual orientation of an artificial earth is discussed. The change is due to the presence of a small perturbing moment, which is constant in fixed axes relative to the satellite. It is also shown that the averaged equations in this problem can be integrated

Axial anomaly and the delta_{LT} puzzle

The axial anomaly contribution to generalized longitudinal-transverse polarizability $\delta_{LT}^{}$ is calculated within Regge approach. It is shown that the contribution from the exchange of the $a_1^{}(1260)$ Regge trajectory is nontrivial and might have the key role to explain the large difference between the predictions of chiral perturbation theory and the experimental data for the neutron $\delta_{LT}^{}$. We also present the prediction for the proton $\delta_{LT}^{}$, which will be measured at the Thomas Jefferson National Accelerator Facility in near future.Comment: 5 pages, 3 figures, REVTeX, to be published in Phys. Rev.

Spin exchange in quantum rings and wires in the Wigner-crystal limit

We present a controlled method for computing the exchange coupling in strongly correlated one-dimensional electron systems. It is based on the asymptotically exact relation between the exchange constant and the pair-correlation function of spinless electrons. Explicit results are obtained for thin quantum rings with realistic Coulomb interactions, by calculating this function via a many-body instanton approach.Comment: 7 pages, 2 figures. Changes in the text and figures to improve readability; added reference

Absorption in Ultra-Peripheral Nucleus-Atom Collisions in Crystal

The Glauber theory description of particle- and nucleus-crystal Coulomb interactions at high-energy is developed. The allowance for the lattice thermal vibrations is shown to produce strong absorption effect which is of prime importance for quantitative understanding of the coherent Coulomb excitation of ultra-relativistic particles and nuclei passing through the crystal.Comment: 8 pages, LaTe

Quark-hadron duality for K0−K0ˉK^0-\bar{K^0} mixing

Long distance contribution to the $K^0-\bar K^0$ mixing is taken into account consistently and the corrections to the naive duality result represented by the famous box diagram are found to be small. Estimates are given in the leading order of the chiral perturbation theory.Comment: 11 pages, Late

Calculating loops without loop calculations: NLO computation of pentaquark correlators

We compute next-to-leading order (NLO) perturbative QCD corrections to the correlators of interpolating pentaquark currents. We employ modular techniques in configuration space which saves us from the onus of having to do loop calculations. The modular technique is explained in some detail. We present explicit NLO results for several interpolating pentaquark currents that have been written down in the literature. Our modular approach is easily adapted to the case of NLO corrections to multiquark correlators with an arbitrary number of quarks/antiquarks.Comment: 23 pages, 1 figure, published version. arXiv admin note: text overlap with arXiv:hep-lat/031001

Various versions of analytic QCD and skeleton-motivated evaluation of observables

We present skeleton-motivated evaluation of QCD observables. The approach can be applied in analytic versions of QCD in certain classes of renormalization schemes. We present two versions of analytic QCD which can be regarded as low-energy modifications of the ``minimal'' analytic QCD and which reproduce the measured value of the semihadronic tau decay ratio r{tau}. Further, we describe an approach of calculating the higher order analytic couplings Ak (k=2,3,...) on the basis of logarithmic derivatives of the analytic coupling A1(Q^2). This approach can be easily applied in any version of analytic QCD. We adjust the free parameters of the afore-mentioned two analytic models in such a way that the skeleton-motivated evaluation reproduces the correct known values of r{tau} and of the Bjorken polarized sum rule (BjPSR) db(Q^2) at a given point (e.g., at Q^2=2 GeV^2). We then evaluate the low-energy behavior of the Adler function dv(Q^2) and the BjPSR db(Q^2) in the afore-mentioned evaluation approach, in the three analytic versions of QCD. We compare with the results obtained in the ``minimal'' analytic QCD and with the evaluation approach of Milton et al. and Shirkov.Comment: 30 pages, 14 eps-figures; v3: parameters of the analytic QCD models M1 and M2 were refined, the numerical results modified accordingly, new paragraph at the end of Sec.II and at the end of Sec.III, discussion of Figs.4 extended, references added; version to appear in PR

Channeling of Relativistic Electrons in Half-Wave Silicon Crystal and Corresponding Radiation

The new experiments on channeling of 255 MeV in a 0.7 ?m silicon half-wavelength crystal were performed at SAGA LS facility. Both experimental and simulated electron angular distribution after the crystal and corresponding radiation spectra reveal the number of peculiarities