Tests for planar events in e+e− annihilation

We present a new class of observables which distinguish events containing two or three hadron jets from those containing a larger number. These observables, which essentially measure the coplanary of events, are calculable in QCD perturbation theory. Their use should allow the mechanism of

decay to be determined.     

Duality ine + e − annihilation

With the help of a relativistic generalization of the formula for the leptonic width of quarkonium in the semiclassical approximation it is shown that for any confinement potential nonsingular at the origin the sum of total cross sections for the production of the heavy quarkonium states \((Q\bar Q)_n\) with masses \(M_n \leqq \sqrt s\) ine ⁺ e ^?-annihilation is equal to the cross section at givens for the production of the free quark-antiquark pair \(Q\bar Q\) . We obtain also a family of dual sum rules for quarkonium which are in agreement with the available experimental data on charmonium and beautionium within experimental errors.     

Factorization and transverse momentum for two-hadron production in inclusive e + e − annihilation

We study the factorization of processes involving two fragmentation functions in the case of very small transverse momenta. We consider two-hadron production in inclusive e ⁺ e ⁻ annihilation and demonstrate a new simple and illustrative method of factorization for such processes, including leading order α _s corrections. The text was submitted by the authors in English.     

Average temperature and multiplicities ofe + e − annihilation

Hadron temperatures ofe ⁺ e ^?→h \(\bar h\) from PEP experiments at 29 GeV are estimated using theP _⊥ distribution; rather small fluctuations are found for temperatures of π,K,..., Ξ with respect to the average \(\bar T = 196 \pm 7\) MeV. A semi-empirical formula including quark content ofh is proposed to account for multiplicities of π,K, ..., Δ in terms of a unique temperature \(\bar T\) . The formula is further extended to charmed particlesD, F, J/Ψ andΛ _c without free parameters. The property \(\bar T\) ~E _cm ^1/4 holds for other experiments of DESY andCESR.     

Jet masses in e+e− annihilation

We calculate heavy (M _H ² /s) and light (M _L ² /s) jet masses up toO(α _s ² ) in perturbative Quantum Chromodynamics (QCD). The sensitivity of these quantities to radiative corrections, quark masses, fragmentation effects as well as their infrared stability properties, are investigated and compared to those exhibited by other jet measures. A comparison with recent Mark II data is also presented.     

Production and decay of neutralinos in e+e− annihilation

We study in detail production and decay of neutralinos in e⁺e⁻ annihilation. Formulae for the cross section, the single lepton, lepton pair, and missing energy spectra are given. Particular attention is paid to the mixing of gauginos and higgsinos. In order to illustrate its importance numerical results for four different mixing scenarios are presented.     

Rapidity distribution ine + e − annihilation

A method to systematically calculate the rapidity distribution of hadrons in a high-energy jet is formulated in terms of an integral equation for the multiplicity. The distribution has the following properties at high energies: (i) a translational invariance; (ii) an increasingly steep distribution with a width proportional to \(\sqrt {\ln s} \) , but without a widening “central plateau”; (iii) if the rapidity is scaled by \(\sqrt {\ln s} \) , it approaches to a universal exponential curve. In the large rapidity region, however, the translational invariance is broken because of the recoil of the quark by the emission of soft gluons. It is also discussed that a gluon jet has a wider angular distribution.     

Isoscalar amplitude dominance in e + e − annihilation to N N̄ pair close to the threshold

We use the Paris nucleon-antinucleon optical potential for explanation of experimental data in the process e ⁺ e ^? → p p? near threshold. It turns out that final-state interaction due to Paris optical potential allows us to reproduce available experimental data. It follows from our consideration that the isoscalar form factor is much larger than the isovector one.     

Two-jet cross section ine + e − annihilation

We calculate the two-jet cross section in order α _s ² in the framework of massless perturbative QCD, using for jet resolution the jet mass. We derive results for two different approaches. One approach is based on the singularity structure of the various contributions. The other one is adjusted to the methods used in three- and four-jet calculations so that the total cross section can be reconstructed.     

Perturbative QCD coherence ine + e − annihilation

We study the pattern of soft parton radiation in the hard annihilation processes \(e^ + e^ - \to q\bar q\gamma \) and \(e^ + e^ - \to q\bar qg\) by explicit evaluation of the cross sections for \(e^ + e^ - \to q\bar q\gamma g\) and \(e^ + e^ - \to q\bar qgg + q\bar qq\bar q\) taken care of correct normalization. We find the coherence effects as observed experimentally and discuss why these effects are not present in the usual models based onO(α _s ² ) perturbation theory with subsequent independent fragmentation.     

Double P-wave charmonium production in e + e − annihilation

On the basis of perturbative QCD and relativistic quark model we calculate relativistic and bound state corrections in the production processes of a pair of \(\mathcal{P}\) -wave charmonium states. Relativistic factors in the production amplitude are taken into account connected with the relative motion of heavy quarks and the transformation law of the bound-state wave function to the reference frame of the moving \(\mathcal{P}\) -wave mesons. Relativistic corrections to the quark bound-state wave functions in the rest frame are considered by means of the Breit-like potential. It turns out that the examined effects change essentially nonrelativistic results of the cross section for the reaction e ⁺ + e ^? → h _c + χ _c J at the center-of-mass energy √s = 10.6 GeV.     

D* meson production cross sections in e − p and e + p scattering processes at the HERA collider

The cause of the D* meson production cross sections in e ^? p and e ⁺ p deep inelastic scattering processes in the ZEUS experiment at the HERA collider that are anomalously different is determined.     

Covariant partition temperature model ande + e − annihilation

The rapidity distributions of inclusive \(e^ + e^ - \to h\bar h + \cdot \cdot \cdot\) of PEP and DESY experiments are analyzed in terms of the covariant partition temperatureT _p model. The estimates ofT _p ^* in the fireball system are comparable to the conventional temperature, the energy dependence follows approximately Stefan's law, the radius of the specific volume ralative to the energy density being ～1.18 fm. In the c.m.s. of collision, \(T_p = AW^a (W = \sqrt s in GeV)\) witha=0.60±0.05 andA=0.256±0.006, it is found \(T_p \cong {W \mathord{\left/ {\vphantom {W {\tfrac{3}{2}\left\langle {n_ \pm } \right\rangle }}} \right. \kern-0em} {\tfrac{3}{2}\left\langle {n_ \pm } \right\rangle }}\) . These properties hold also for \(\bar pp\) collision, but not forpp→π^?+...     

W+W−γ production in e+e− annihilation in the TeV region

The reaction e⁺e⁻→γW⁺W⁻ has been studied at TeV energies as a possible background to Higgs production. Our results differ significantly from previous estimates and show that the ratio signal/background can be kept reasonably large.     

Perturbative relations between e+e− annihilation and τ decay observables including resummation effects

By exploiting the analyticity properties of the two-point current-current correlator we obtain numerical predictions for the e⁺e⁻ moments in terms of the τ decay rate. We perform a partial resummation of the pertinent perturbative series expansion by solving the renormalization group equation for Adler's function. Our predictions are renormalization scheme independent but depend on the order of the perturbative β-function expansion. The analysis involves the unknown five-loop coefficient k₃ for which we give some new estimates.