The effects of the charged gluon jets in the transversely polarized e+e− annihilation

The lowest order calculations of the process of e⁺e^?→jets are extended to the case of transversely polarized e⁺e^? beams in the Pati-Salam model. The results are not significantly different from those of the QCD in the lowest order.     

Possible tests of scale invariance in very high-energy e+e− collisions

The differential cross section for the process e⁺e^? → e⁺e^?X is connected to properties of the asymptotic zero mass theory. Assuming Wilson's expansion relations between different measurable quantities are obtained.     

Charged majorons ine + e − ande − e − collisions

The experimental limits on charged majorons, i.e. charged scalars which carry lepton number, are discussed in a model independent way. Possible signals ine ⁺ e ^? ande ^? e ^? collisions are then estimated. It is stressed that the limits on majorons which conserve the different lepton flavors separately are presently very poor. These limits can however be improved by studyinge ^? e ^? collisions.     

Hunting new vector bosons in high precision measurements without polarization

We illustrate a strategy to identify the effect of a possible extra neutral vector boson of several different theoretical origins (extended gauge groups, composite models, models with a strongly interacting Higgs sector), assuming that only precision experiments without polarized e⁺e⁻ beams were available. We show that it might be relatively easy to discover evidence of genuine New Physics (i.e., effects not depending on the value of the top mass, or on the existence of new families...) if a certain set of observables, including the final τ polarization in unpolarized e⁺e⁻ annihilation, were measured. The region of possible confusion between different theoretical models would be, though, sensibly larger than in the case in which e⁺e⁻ polarization were available.     

Resolution of the O(αs2) shape variable controversy for e+e− annihilation

The differences among recent calculations of the O(α_s²) QCD corrections to shape variable distributions for e⁺e^? annihilation are shown to arise from different underlying definitions of jets and jet observables. In particular, the Caltech (large corrections) and DESY (small corrections) results are not obviously contradictory. We raise questions on the validity of all such calculations for the precise empirical determination of α_s from data for e⁺e^?→ hadrons.     

Supersymmetry and polarization in e+e− collisions (II). Fermionic partners of the gauge bosons

We study the pair production of fermionic partners of the gauge bosons in e⁺e^? collisions with polarized beams. We calculate the cross sections and the spin asymmetries for various processes using different models for the basic properties of gauginos. If they exist and if they are rather light, they should be discovered in future e⁺e^? colliders. We show that polarization provides very special signatures for their experimental search.     

Electron-positron pair production as a probe of chiral symmetry in a hot QCD plasma

Chiral symmetry in the high-temperature plasma phase of QCD is consistent with at least three qualitatively different quark dispersion relations. The rate for $\text{q}\text{q}\text{→}\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}$, with zero total momentum of the e⁺e^? pair in the plasma rest frame is direct measure of the quark dispersion relation. For the three plausible dispersion relations the rates differ by orders of magnitude when the e⁺e^? invariant mass M < 2T.     

ee Annihilation into two hadrons in the energy interval 1400–2400 MeV

The proof is given for the existence of the reaction e⁺e⁻ → h^±h^? in the energy range 1400–2400 MeV, and its energy dependence is compared with that of e⁺e⁻ → e^±e^?, in the same experimental conditions of observation. The exponent of the s-dependence of the ratio α = (e⁺e⁻ → h^±h^?)/ (e⁺e⁻ → e^±e^?) is measured to be n = 2.08 ± 0.45, in the s-range (1.96 − 5.76) GeV², on the basis of 51 e⁺e⁻ → h^±h^? events and 8918 e⁺e⁻ → e^±e^? events observed.     

Quantisation of the string fragmentation model

We quantise the classical Artru-Mennessier string model with a Feynman sum over histories method. This procedure yields both propagation amplitudes and a Veneziano mass spectrum for mesons, with resonance poles for unstable states. Applied to the processe ⁺ e ^?→hadrons our amplitudes justify previous applications of string models and in particular the relative amplitudes for different string configurations are in agreement with a recent conjecture of Andersson and Hofmann which can account for the observed Bose-Einstein correlations ine ⁺ e ^? annihilation.     

Hard photon corrections for Bhabha scattering

Numerical results for the α³ differential cross section for e⁺e^? → e⁺e^? are presented for the case of e⁺e^? colliding beams. Special care is given to the hard photon corrections. Acoplanarity distributions for e⁺e^? → e⁺e^?γ are also presented. Attention is drawn to experimental conditions which require the calculation of still higher order corrections.     

Analyzing thee + e −→e + e − angular distibution at LEP

The analysis of the lepton angular distribution at LEP is reviewed and the specific concerns in the case ofe ⁺ e ^– final state are singled out. Studies of the physical information contained in thee ⁺ e ^– angular distribution are shown to justify the need for a new approach. Two different solutions that enable the complete use of the angular distribution information for the extraction of theZ parameters are presented. We show that these approaches have accuracies well above the future experimental needs.     

Z boson effects in electron positron scattering at epic energies at 14 GeV

We discuss the problem of testing the intermediate vector boson effects in the reactions e^?e⁺ → e^?e⁺ + hadrons, e^?e⁺ → e^?e⁺ + μ^?μ⁺, e^?p → e^?x with the next generation of accelerators, and conclude that these reactions must be considered. The differential cross sections for the one lepton at large four-momentum transfer are obtained, and a significant contribution of Z effects is found.     

e+e− Annihilation into two and three photons at high energy

Analytical expression for the total cross section and for different spectra in the process e⁺e^? → 3γ have been obtained accurate to a given power in the energy.     

Analysis of triplet production by a circularly polarized photon at high energies

The possibility in principle of determining the circular polarization of a high-energy photon by measuring the created electron polarization in the process of triplet photoproduction γ + e ^? → e ⁺ e ^? + e ^? is investigated. The respective event number, which depends on polarization states of the photon and the created electron, does not decrease as the photon energy increases, and this circumstance can ensure the high efficiency in such experiments. We study different double and single distributions of the created electron (or positron), which allow probing the photon circular polarization and measuring its magnitude (the Stokes parameter ξ₂) using the technique of Sudakov variables. Some experimental setups with different rules for event selection are studied and the corresponding numerical estimations are presented.     

Investigation of the dependence of the e<Subscript>0</Subscript>-electron yield on the radioactive decay location in <Superscript>64</Superscript>Cu sources

The yields of near-zero-energy e₀ electrons from sources of different thickness in the ⁶⁴Cu decay have been measured. At small thicknesses of the ⁶⁴Cu source, the e₀-electron yield Y _e sharply increases and is qualitatively described by the dependence Y _e ～ r ^?2, where r is the distance from the point of charge formation to the source surface.     

The muon spectra from decays ofW- andZ-bosons produced ine + e −-collisions

The muon spectra from the decays ofW-andZ-bosons, produced ine ⁺ e ^?→W ⁺ W ^?,e ⁺ e ^?→Zγ,e ⁺ e ^?→ZZ ande ⁺ e ^?→ZH reactions have been obtained (H is the Higgs boson). It has been shown (in terms of Glashow-Weinberg-Salam theory) that the main source of muons are thee ⁺ e ^?→Zγ ande ⁺ e ^?→W ⁺ W ^? processes (over theW-boson production threshold). The contribution of thee ⁺ e ^?→ZZ ande ⁺ e ^?→ZH reactions to the inclusive muon spectra is small. It has been also shown, that it is possible to distinguish contributions of thee ⁺ e ^?→Zγ ande ⁺ e ^?→W ⁺ W ^? reactions if the decay muons move at a small angle to the initial electron momentum.     

Jet production in e+e− collisions to order α3 and α4 and including QCD corrections

Cross sections for e⁺e^?→jet₁ + jet₂ + X are calculated to order α³ and α⁴ in the electromagnetic coupling and to arbitrary order in α_s in the leading logarithm approximation of QCD. Physically the processes included are the emission of hard protons from the incident e^± followed by annihilation, photon-proton scattering and deep inelastic scattering on an electron. The experimental separation of the mechanisms on the basis of their different event structure is discussed.     

Screening effect of the coulomb interaction on the energy levels of atomic and molecular systems

The energies of atomic and molecular systems with a screened Coulomb interaction are expressed in terms of properties of the system with a conventional Coulomb interaction to the third order in the screening constant. The energy levels of an H atom, an H^? ion, and nonadiabatic systems, namely, the positronium ion e ⁺ e ^? e ^? and the positronium molecule e ⁺ e ⁺ e ^? e ^?, are calculated for screened Coulomb interactions of charged particles. It is demonstrated that, as the screening constant of the Coulomb interaction increases, the stability of the hydrogen atom, the H^? ion, and the positronium molecule e ⁺ e ⁺ e ^? e ^? decreases, whereas the stability of the positronium ion e ⁺ e ^? e ^? increases after a slight decrease.