### Regular Series

#### Vol. 17 (1986), No. 5, pp. 391 – 478

Polarized $\gamma$-Quanta Production in $\tau \to \nu + \pi + \gamma$ Decay

Acta Phys. Pol. B 17, 391 (1986)

page 391 •

abstract

The Stokes parameters of the photons produced in the $\tau$-lepton decay, $\tau \to \nu + \pi + \gamma$, have been found. The study of $\gamma$-quanta polarization parameters in this decay allows us to obtain the essential information about the vector and axial formfactors of $\gamma$W$\pi$ vertex in a broad interval of the time like momentum transfer which are inaccessible in the radiative pion decay. We have calculated the contribution in the Stokes photon parameters which is caused by the anomalous magnetic moment of a heavy lepton.

$P$-Odd Asymmetries in Deep Inelastic Scatterings of Polarized Leptons on Nuclei

Acta Phys. Pol. B 17, 401 (1986)

page 401 •

abstract

The $P$-odd asymmetries in deep inelastic scatterings (DIS) of polarized leptons on nuclei are considered in the framework of the standard model and the parton-flucton model (Tran Huu Phat, Le Si Hoi, Tran Duy Khuong, Acta Phys. Austriaca 57, 33 (1985)). The model predictions, within the experimental errors, agree well with the present data.

The Background Field Method in the Axial Gauge

Acta Phys. Pol. B 17, 409 (1986)

page 409 •

abstract

The background field method is applied to Yang–Mills theories (e.g. QCD) in the axial gauge. It provides a simple and elegant way to obtain relations between renormalization constants in QCD. Constraints on the form of gauge-fixing conditions in the background field method are derived.

Periodic Solutions of Yang–Mills–Dirac Theory

Acta Phys. Pol. B 17, 417 (1986)

page 417 •

abstract

New periodic in time and space independent solutions of Yang–Mills equations coupled to massless Dirac bispinors are presented.

On Summation of Perturbation Expansions

Acta Phys. Pol. B 17, 425 (1986)

page 425 •

abstract

The problem of the restoration of physical quantities defined by divergent perturbation expansions is analysed. The Padé and Borel summability is proved for alternating perturbation expansions with factorially growing coefficients. The proof is based on the methods of the classical moments theory.

Direct Photon Production

Acta Phys. Pol. B 17, 435 (1986)

page 435 •

abstract

First, I summarize the physics issues involved in studies of prompt photons in hadronic collisions at large transverse momenta ($p_{\rm T}$); next, I review the latest comparisons between data and predictions from QCD; finally, I discuss some of the features of a second-generation experiment at Fermilab (E706) that is designed to study the flavor dependence of direct photon production at beam energies of 600–900 GeV.

Is Our Metric a Fixed Point on a Fractal?

Acta Phys. Pol. B 17, 449 (1986)

page 449 •

abstract

The study of a discrete version of Laplace equation on a fractal is presented. While in the limit $n \to \infty$ the solutions of the equations are close to the usual ones in the continuum, a new essential feature appears, namely the presence of fixed points in the metric.

A Model for Low-$p_{\rm T}$ Processes Based on Classical String Dynamics

Acta Phys. Pol. B 17, 457 (1986)

page 457 •

abstract

We review a recursive fragmentation model of low-$p_{\rm T}$ jets, based on classical string dynamics, which possesses all the qualitative features of the multiperipheral model and Regge asymptotic behaviour. The parameters of the model are uniquely determined by the Regge trajectories and the reggeon vertex functions. We apply this model to multiparticle states corresponding to the cut reggeons and the cut pomerons.

Electromagnetic Mass Differences of Mesons in a QCD Potential Model

Acta Phys. Pol. B 17, 471 (1986)

page 471 •

abstract

Considering the gluonic contribution to mass difference in the non-relativistic QCD potential model of Schnitzer, we calculate the electromagnetic mass differences of strange, charm, $b$-quark and $t$-quark mesons. The numerical results are found to be in agreement with the available experimental values and with the theoretical values of others. We predict $T^+(\bar dt)- T^0(\bar ut) \simeq T^{*+}-T^{*0}\simeq$ 3.6 MeV.

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