Murat M. Kaskulov

The properties of the three-nucleon system with the dressed-bag model for NN interaction: I. New scalar three-body force

A multi-component formalism is developed to describe three-body systems with nonstatic pairwise interactions and non-nucleonic degrees of freedom. The dressed-bag model for NN interaction based on the formation of an intermediate six-quark bag dressed by a σ-field is applied to the 3N system, which results in a new three-body force between the six-quark bag and a third nucleon. Concise variational calculations of 3N bound states are carried out in the dressed-bag model including the new three-body force. It is shown that this three-body force gives at least half the 3N total binding energy, while the weight of non-nucleonic components in the 3 H and 3 He wavefunctions can exceed 10%. The new force model provides a very good description of 3N bound states with a reasonable magnitude of the aNN coupling constant. The model can serve as a natural bridge between dynamical description of few-nucleon systems and the very successful Walecka approach to heavy nuclei and nuclear matter.

Single- and double-pion production in nucleon collisions on the nucleon and on nuclei—the ABC effect and its origin in a dibaryonic resonance

Abstract The ABC effect–an intriguing low-mass enhancement in the π π invariant mass spectrum–is known from inclusive measurements of two-pion production in nuclear fusion reactions. First exclusive measurements carried out at CELSIUS-WASA for the fusion reactions leading to d or 3 He reveal this effect to be a σ -channel phenomenon associated with the formation of a Δ Δ system in the intermediate state and combined with a resonance-like behavior in the total cross-section. Together with the observation that the differential distributions do not change in shape over the resonance region the features fulfill the criteria of an isoscalar s-channel resonance in p n and N N π π systems, if the two emitted nucleons are bound. It obviously is robust enough to survive in nuclei as a dibaryonic resonance configuration. In this context also the phenomenon of N Δ resonances is reexamined.

A dressed-bag model study of the short-range NΔ interaction in pion photoproduction processes off the deuteron

The impact of the short-range NΔ interaction on the pion photoproduction processes off the deuteron in the Δ-resonance region is studied in the framework of a recently proposed dressed-bag model. A common dressing procedure for bare three- and six-quark states is used to describe both the pion decay widths of baryon resonances and the effective NN (or NΔ) interaction at short ranges. It is shown that the effect of short-range NΔ interaction for the forward-angle π0 photoproduction off the deuteron cannot be neglected. The prospects for further development of the model to describe the short-range NN (or NΔ) correlations in the lightest nuclei are discussed.

Hadrons in nuclei from high (200 GeV) to low (1 GeV) energies

Abstract The study of the interaction of hadrons, produced by introducing elementary probes into a nucleus, with the surrounding nuclear medium can give insight into two important questions. Firstly, at high energies, the production process, the time-scales connected with it, and the prehadronic interactions can be studied by using the nuclear radius as a length-scale. We do this here by analyzing data from the EMC and HERMES experiments on nuclear attenuation. Secondly, at low energies the spectral function, and thus the selfenergy of the produced hadron, can be studied. Specifically, we analyze the CBELSA/TAPS data on ω production in nuclei and discuss the importance of understanding in-medium effects both on the primary production cross section and the final state branching ratio. In both of these studies, an excellent control of the final state interactions is essential.

Deep exclusive electroproduction of {pi}{sup +} from data measured with the HERMES detector at DESY

Deeply virtual electroproduction of pion in exclusive reaction p(e, e′π+)n is studied using a twocomponent model which includes soft hadronic and hard partonic reaction mechanisms. The results are compared with the experimental data measured at HERMES in the deep inelastic region for values of Q2 > 1 GeV2 and W 2 > 10 GeV2. At forward angles the π+ cross section is longitudinal and is dominated by exchange of Regge poles, with π the dominant trajectory. The off-forward region with −t > 1 GeV2 is transverse and shows the dominance of partonic subprocesses. An implication of present results for the future JLAB facilities are briefly discussed. ∗Electronic address: murat.kaskulov@theo.physik.uni-giessen.de

On the background in the \( \gamma\)p \( \rightarrow\)\( \omega\)(\( \pi^{0}_{}\)\( \gamma\))p reaction and mixed event simulation

Abstract.In this paper we evaluate sources of background of the

The electric form factor of the neutron and its chiral content

\ensuremath\gamma p \rightarrow \omega p

Effect of gluon-exchange pair currents on the ratioμpGEp/GMp

reaction, with the

Magnetization screening from gluonic currents and scaling law violation in the ratio of magnetic form factors for neutron and proton

\omega

A Dressed Bag Study of the d(γ π) 2N Reaction

detected through its