I. Øverbø

Gluon bremsstrahlung in e+e- annihilation: (I). Neutral current and beam polarization effects

The cross section for gluon bremsstrahlung, e+e− → qqg, is calculated for the case of arbitrarily polarized electron-position beams, including weak interaction effects, in the Glashow-Weinberg-Salam model. The weak neutral current effects somewhat reduce the dependence of the cross section on transverse beam polarization, and lead to a rotation of the azimuthal distributions, as compared with the low-energy limit. This leads to flavour separation, in the sense that the azimuthal distributions are different for up and down quark flavours.

KAZAMA-YANG MONOPOLE - FERMION BOUND STATES. 1. ANALYTIC RESULTS

Abstract We present explicit, approximate, remarkably precise results for the Kazama-Yang monopole-fermion binding energies and wave functions. The results are valid for the states of lowest angular momentum and for the binding energy M − E ⪡ M . They agree very well with the numerically calculated values.

Polarized gluon bremsstrahlung as a test of QCD

Abstract Gluon bremsstrahlung emitted in electron-positron annihilation at high energies is found to have a remarkably high degree of linear polarization. It is suggested that measurements of the gluon polarization through angular correlations in the decay of isoscalar vector mesons or possibly through gluon jet oblateness could constitute sensitive test of QCD.

Flavour separation by means of transverse beam polarization in high-energy e+e- annihilation

Abstract Transverse beam polarization is in e + e - annihilation at high energies shown to lead to a strong azimuthal variation in the flavour composition of the produced quark-antiquark pairs. We describe, in the SU(2) × U(1) model, a way in which this could be used to obtain flavour-specific information on the quark fragmentation functions. In inclusive charged particle rates the effect might be much reduced, but still observable.

Very-high-precision solutions of a class of Schrödinger type equations

Abstract We investigate a method to solve a class of Schrodinger type equation eigenvalue problems numerically to very high precision P (from thousands to a million of decimals). The memory requirement, and the number of high-precision algebraic operations, of the method scale essentially linearly with P when only eigenvalues are computed. However, since the algorithms for multiplying high-precision numbers scale at a rate between P 1.6 and P log P log log P , the time requirement of our method increases somewhat faster than P 2 .

Radiative capture of spin-12 particles by magnetic monopoles

Abstract We evaluate the cross section for the radiative capture of spin- 1 2 fermions by monopoles, using wave functions derived from the Kazama-Yang hamiltonian, valid in the limit of low incident relative velocities, β⪡1, and weakly bound states, with binding energies much smaller than the fermion mass, EB⪡M. The cross sections obtained are generally of the order of ( Z 2 α M 2 )( E B 1 2 Mβ 2 ) . The formulae obtained can be used to estimate cross sections for the capture of spin- 1 2 nuclei.

Kazama-Yang monopole-fermion scattering states

Abstract Scattering states of definite helicity are constructed - in terms of partial-wave expansions - for a point fermion with spin 1 2 and an extra magnetic moment in the field of an infinitely heavy Dirac monopole, i.e., with the Kazama-Yang hamiltonian. The approximate solutions thus obtained, which are valid for small velocities, β ⪡1, are useful for evaluating capture cross sections.

Gluon bremsstrahlung in e+e− annihilation: (II). Gluon polarization

Abstract The linear and circular polarizations of gluons emitted in electron-positron annihilation, e + e − → q q g , are evaluated, including neutral current and beam polarization effects. For the lower part of the gluon bremsstrahlung spectrum, the linear polarization is found to be large and the plane of polarization to be almost parallel to the q q g event plane. The neutral current induced circular polarization is in the upper part of the gluon spectrum of the order of 10–15% at 40 GeV total energy and reaches ∼50% at asymptotic energies.

Polarization-Induced Azimuthal Flavour Asymmetries in e+e- Annihilation as a Signature of Neutral Currents

At high energies, transverse beam polarization leads in e+e- annihilation to an azimuthal variation in the composition of the produced particles. This effect has its origin in the flavour dependence of the ratio between the right- and left-handed components of the neutral current. The detection and identification of particles which are dominantly produced by quarks of one or a few specific flavours, would allow for an observation of this neutral-current effect. We estimate the resulting azimuthal asymmetries in the rates for the production of B, D and F mesons to be of the order of 5–10% at \(\sqrt {{Q^2}} \simeq 40 - 50\,GeV\).

Determination of the Gluon Spin via Polarized Gluon Bremsstrahlung

According to perturbative QCD, gluons radiated in electron-positron annihilation are linearly polarized in the (qqg) event plane. In large parts of phase space this polarization is close to complete. We point out that this offers a possibility for direct observation of the vector nature of the gluon, by a measurement of the linear polarization of leading isoscalar vector mesons originating in the gluon jets.