M. Kaskulov

Inclusive ω photoproduction from nuclei and ω in the nuclear medium

Abstract.With the aim of extracting information on the shift of the ω mass in the nuclear medium we analyze data obtained at ELSA from where claims for evidence of a mass shift of the ω have been made. We develop a Monte Carlo simulation code which takes into account the possible reactions in the experimental set-up of (γA → π0γX) in the vicinity of the ω production region with subsequent ω → π0γ decay. We compare our results with experiment for the distribution of π0γ invariant masses and conclude that the distribution is compatible with an enlarged ω width of about 90MeV at nuclear-matter density and no shift in the mass. This change in the width would be compatible with the preliminary results obtained from the transparency ratio in the A-dependence of ω production. The discrepancy of the present conclusions with former claims of an evidence for a shift of the ω mass stems from a different choice of background which is discussed in the paper.

Possible ω bound states in nuclei produced with the (γ, p) reaction

We perform calculations for {omega} production in nuclei by means of the ({gamma},p) reaction for photon energies and proton angles suited to currently running and future experiments in present laboratories. For some cases of possible {omega} optical potentials, we find that clear peaks are observable when a good resolution in the {omega} energy is available. We also study the inclusive production of {pi}{sup 0}{gamma} in nuclei around the {omega} energy and find a double hump structure for the energy spectra, with a peak around a {pi}{sup 0}{gamma} energy of m{sub {omega}}-100 MeV, which could easily be misidentified by a signal of an {omega} bound state in nuclei, while it is actually due to a different scaling of the uncorrelated {pi}{sup 0}{gamma} production and {omega} production with subsequent {pi}{sup 0}{gamma} decay.

Lambda (1520) and Sigma (1385) in the nuclear medium

Recent studies of the {lambda}(1520) resonance within chiral unitary theory with coupled channels find the resonance as a dynamically generated state from the interaction of the decuplet of baryons and the octet of mesons, essentially a quasibound state of {pi}{sigma}{sup *}(1385) in this case, although the coupling of the {lambda}(1520) to the KN and {pi}{sigma} makes this picture only approximate. The {pi}{sigma}{sup *}(1385) decay channel of the {lambda}(1520) is forbidden in free space for the nominal mass of the {sigma}{sup *}(1385), but the coupling of the {pi} to ph components in the nuclear medium opens new decay channels of the {lambda}(1520) in the nucleus and produces a much larger width. Together with medium modifications of the KN and {pi}{sigma} decay channels, the final width of the {lambda}(1520) at nuclear matter density is more than five times bigger than the free one. We perform the calculations by dressing simultaneously the {lambda}(1520) and the {sigma}{sup *}(1385) resonances, finding moderate changes in the mass but substantial ones in the width of both resonances.

A-dependence of the γ- and p-induced production of the Λ(1520) from nuclei

Abstract.Using results of a recent calculation of the Λ(1520) in the nuclear medium, which show that the medium width is about five times the free width, we study the A-dependence of the Λ(1520) production cross-section in the reactions γA → K+Λ(1520)A′ and pA → pK+Λ(1520)A′. We find a sizable A-dependence in the ratio of the nuclear cross-sections for heavy nuclei with respect to a light one due to the large value of the Λ(1520) width in the medium, showing that devoted experiments, easily within reach in present facilities, can provide good information on that magnitude by measuring the cross-sections studied here.

Two pion mediated scalar isoscalar NN interaction in the nuclear medium

We study the modification of the nucleon nucleon interaction in a nuclear medium in the scalar isoscalar channel, mediated by the exchange of two correlated (� channel) or uncorrelated pions. For this purpose we use a standard approach for the renormalization of pions in nuclei. The corrections obtained for the NN interaction in the medium in this channel are of the order of 20% of the free one in average, and the consideration of short range correlations plays an important role in providing these moderate changes. Yet, the corrections are sizable enough to suggest further studies of the stability and properties of nuclear matter.

Λ(1520) at finite density

We study the decay channels of the

Study of possible omega bound states in nuclei with the (gamma,p) reaction

Lambda(1520)

Selected topics on Hadrons in Nuclei

in a nuclear medium and find a sizable change - of the order of factor five - of the width of this hyperon at normal nuclear matter density. The mass shift of the

Recent Developments in Chiral Dynamics of Hadrons and Hadrons in Nuclei

Lambda(1520)

Recent developments in chiral dynamics of hadrons and hadrons in a nuclear medium

is moderate.