Ya.I. Azimov

THE STRING EFFECT AND QCD COHERENCE

Abstract In the framework of the idea of local parton-hadron duality we discuss the asymptotic predictions of QCD perturbation theory for angular distributions of hadron flows in three-jet events, e + e - → q q g → hadrons. The coherence of soft gluon emission provides the QCD explanation of the string effect observed in experiments.

CP VIOLATING EFFECTS IN e+e - ANNIHILATION

We discuss possibilities of measuring CP violation in e+e− annihilation by means of studying final-state correlations. Since the contribution of K ⇌ K-type oscillations in the D0, G0 (bd) and H0 (bs) meson decays are expected to be small, we suggest a method which allows to observe CP violating effects in the decays even in the absence of the oscillations. The method is equally applicable to charged meson and baryon decays.

On the possible existence of a new nucleon state

Abstract Nucleon state in one unitary multiplet with Σ(1475) is discussed. It seems to be possible that its mass is below the πN threshold.

The processes of diffraction dissociation at small momentum transfer as a way of studying the asymptotics of total cross sections

It is shown that the energy dependence of forward diffraction dissociation enables one to distinguish experimentally between the theory with asymptotically constant total cross sections and other possibilities. In the framework of this theory, characteristic features of diffraction processes are considered and estimates are given for changes of total and forward diffraction cross sections in the available energy range under different assumptions on many-pomeron cut contributions.

Quark structure and radiative decays of new particles

Abstract Parameters of the heavy and light quarks mixing in singlet and triplet states are found from the data on decays of Ψ(3.1). The results agree with expectations based on ideas of asymptotic freedom.

Properties of the Λ(1520) resonance from high-precision electroproduction data

Abstract High-resolution spectrometer measurements of the reaction H ( e , e ′ K + ) X at small Q 2 are used to extract the mass and width of the Λ ( 1520 ) . We investigate the influence of various assumptions used in the extraction. The width appears to be more sensitive to the assumptions than the mass. To reach a width uncertainty about 1 MeV or better, one needs to know the structure of the non-resonant background. Based on the new Jefferson Lab Hall A data, our final values for the Breit–Wigner parameters are M = 1520.4 ± 0.6 (stat.) ± 1.5 (syst.) MeV , Γ = 18.6 ± 1.9 (stat.) ± 1 (syst.) MeV . We also estimate, for the first time, the pole position for this resonance and find that both the pole mass and width seem to be smaller than their Breit–Wigner values.

On the energy spectra of the secondary e or μ in the reaction e+e− → L+L−

Decay products of heavy leptons L± produced in the process e+e− → L+L− are studied. Exact expressions for the energy spectra of secondary electrons or muons are given. It is shown that specific features of the spectra allow one to identify the heavy lepton production in e+e− annihilation and to determine masses of both the lepton L± and its neutral partner νL. Calculations are made under the assumption of V ± A structure of the (LνL) current.