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Register a new userModels for photo- and electro-production of K^+ in view of new data
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Authors
P. Bydzovsky
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Predictions of isobaric and Regge models are compared with the latest experimental data (Bonn,JLab) to select among the models those providing a satisfactory description of the data. Only the Saclay-Lyon and MAID models are in a reasonable agreement with both photo- and electro-production data ranging up to about 2.5 GeV.
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The characteristic and selective nature of the electro-magnetic production of Lambda-hypernuclei in exciting states is demonstrated assuming the medium-mass targets 28Si, 40Ca, and 52Cr. Formalism of DWIA is used adopting the Saclay-Lyon, Kaon-MAID, Adelseck-Saghai, and Williams-Ji-Cotanch models for the elementary amplitudes and various nuclear and hypernuclear wave functions. The elementary amplitudes are discussed in detail presenting their basic properties and comparison with data. The unique features of the electro-magnetic production of Lambda-hypernuclei shown on examples are the slective excitation of unnatural parity highest-spin states (natural parity ones for the LS-closed targets) and a possibilty to investigate the Lambda single-particle energies including a spin-orbit splitting using variety of medium-mass targets.
We summarize the pertinent experimental and theoretical developments in the field of pion photo- and electroproduction in the threshold region. We discuss which experiments and which calculations should be done/performed in the future.
First comprehensive data on the evolution of nucleon resonance photocouplings with photon virtuality Q^2 are presented for excited proton states in the mass range from 1.4 to 2.0 GeV. N^* photocouplings were determined in phenomenological analysis of CLAS data on 2 pi photo and electroproduction within the framework of the JLAB-MSU phenomenological model.
In these lectures I will show some results obtained with the chiral unitary approach applied to the photo and electroproduction of mesons. The results for photoproduction of $eta pi^0 p$ and $K^0 pi^0 Sigma^+$, together with related reactions will be shown, having with common denominator the excitation of the $Delta(1700)$ resonance which is one of those dynamically generated in the chiral unitary approach. Then I will show results obtained for the $e^+ e^- to phi f_0(980)$ reaction which reproduce the bulk of the data except for a pronounced peak, giving support to a new mesonic resonance, X(2175). Results will also be shown for the electromagnetic form factors of the $N^*(1535)$ resonance, also dynamically generated in this approach. Finally, I will show some results on the photoproduction of the $omega$ in nuclei, showing that present experimental results claiming a shift of the $omega$ mass in the medium are tied to a particular choice of background and are not conclusive. One the other hand, the same experimental results show unambiguously a huge increase of the $omega$ width in the nuclear medium.
We present recent results on the production, spectra and elliptic flow of strange particles in dynamic simulations employing hadronic degrees of freedom and from recombination models. The main focus will be on the Ultra-relativistic Molecular Dynamics (UrQMD) Boltzmann approach to relativistic heavy ion collisions and a hybrid approach with intermediate hydrodynamic evolution based on UrQMD (available for download as UrQMD v3.3). Compared to the standard binary collision approach, an enhancement of the strange particle particle yields is found in the hybrid approach due to the assumption of local equilibration. The production origins of the Phi-meson in the hybrid approach are studied in further detail. We also present results on the transverse momentum spectra of baryon to meson ratios of strange particles. Due to the approximate energy independent scaling of this ratio as a function of p_T we argue, that a maximum in these spectra may not be a unique sign for quark coalescence but can be understood in terms of flow and fragmentation.
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