abstract

We present here the calculations on the \(\psi (3.l)\) photoproduction cross section, \(\delta (\gamma N \to \psi (3.l) +\) anything), within the framework of Drell–Yan mechanism using the modified Kuti–Weisskopf quark parton distributions with a view to assessing the charmed quark contents of the nucleon. Our results show that the charmed quarks in the nucleon must be rarer than the strange quarks by about 50%.

abstract

Charmed quark fragmentation functions are calculated in a Monte Carlo quark–parton recombination model. It is shown that the shape of the fragmentation functions is rather sensitive to the leading behaviour of the charmed quark during the fragmentation process. We argue that the data on charmed meson production can provide useful information about the dynamics of this process.

abstract

We compare the predictions following from the Monte Carlo quark–parton model of multiparticle production with the extensive set of data on antiproton–proton interactions at 22.4 GeV/\(c\) in the 2m bubble chamber Ludmila at Serpukhov. The emphasis is being placed upon such data which may give some information about the distribution of quarks and antiquarks during the intermediate stages of the collision.

abstract

The transverse momentum distribution of the partons is first studied in perturbative QCD in the leading logarithms approximation. The connection of the parton \(k_{\rm T}\) with scaling violation is clarified. The inclusive cross sections for deep inelastic scattering and lepton pair production are then investigated in an extended leading logarithms approximation in which the relevant gluons are allowed to be emitted at arbitrary angles. in that way we obtain general expressions for the inclusive distributions that are valid for any detected transverse momenta \(q_{\rm T}\). The result for lepton-pair production is in a nonfactorizable form. However, upon integration over \(q_{\rm T}\) it leads to \(d\sigma /dM^2\) given by the factorizable Drell–Yan formula. For large \(q^2_{\rm T}\) it also has the usual parton model interpretation. Phenomenological implication of our results is also discussed.

abstract

Simplifications in previously derived nucleon–nucleon solitary exchange potentials are obtained for potentials arising from field theories with self interaction currents of the form \(\lambda _1\phi ^{2q+1}+\lambda _2\phi ^{4q+1}\).

abstract

The potentials \(A^a_i(x)\) of the classical SU(2) Yang–Mills field in temporal gauge are expressed in terms of new variables \(\omega ^a_n(x)\) in a way permitting an explicit separation of ignorable (cyclic) variables in the Hamiltonian.

abstract

Assuming an independent particle production from constituent quarks, the \(A\)-dependence of the spectra of leading and produced particles outside of the target fragmentation region are discussed. The energy and momentum conservation constraints are estimated. The comparison with the data on nucleon and pion induced reactions shows good agreement with the model. Multiplicities in nucleus–nucleus interactions are also computed and compared with cosmic ray data.

abstract

Using a velocity dependent effective potential of s-wave interaction, Hartree–Fock calculations are performed for the doubly even \(N=Z\) nuclei from \(^{12}\)C to \(^{40}\)Ca and odd-\(A\) nuclei in the 2p-1f shell. Values of the binding energy and the quadrupole moment are compared with previous calculations and with experimental data. Reasonable agreement is obtained for the calculated quantities as compared with previous results as well as with experimental data.

abstract

On the IRIS facility in Gatchina the investigations of alpha decay of the short lived rare earth nuclei have been started. The isobare \(A = 157\) has been studied by the on-line isotope separator technique. For the isotope \(^{157}\)Lu the alpha energy 4.995 MeV, \(T_{1/2}=5.5\pm 0.3\) s, and for \(^{153}\)Tm alpha branching ratio \(0.80\pm 0.10\) has been determined.