R. Molina

Examination of experimental evidence of chaos in the bound states of Pb 208

We study the spectral fluctuations of the Pb nucleus using the complete experimental spectrum of 151 states up to excitation energies of 6.20 MeV recently identified at the Maier-LeibnitzLaboratorium at Garching, Germany. For natural parity stat e the results are very close to the predictions of Random Matrix Theory (RMT) for the nearest-neighbo r spacing distribution. A quantitative estimate of the agreement is given by the Brody parameter ω, which takes the value ω = 0 for regular systems andω ≃ 1 for chaotic systems. We obtain ω = 0.85± 0.02 which is, to our knowledge, the closest value to chaos ever observed in experimental bound s tates of nuclei. By contrast, the results for unnatural parity states are far from RMT behavior. We int rpret these results as a consequence of the strength of the residual interaction in Pb, which, according to experimental data, is much stronger for natural than for unnatural parity states. In ad dition our results show that chaotic and non-chaotic nuclear states coexist in the same energy regio n of the spectrum.

Shell-Model studies of chaos and statistical properties in nuclei

Shell-model calculations with realistic empirical interactions constitute an excellent tool to study statistical properties of nuclei. Using large-scale shell-model calculations in pf- shell nuclei, we study how the onset of chaos depends on different properties of the nuclear interaction and on excitation energy. We make use of classical random matrix theory and other theoretical developments based on information theory and time series analysis. We show that besides energy-level statistics, other statistical properties like the complexity of wave functions are fundamental for a proper determination of the dynamical regime of nuclei. Important deviations from GOE are observed in level fluctuations and in the complexity of wave functions.

Charmed hadrons in nuclear medium

We study the properties of charmed hadrons in dense matter within a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a self-consistent manner. We analyze the behaviour in this dense environment of dynamically-generated baryonic resonances as well as the open-charm meson spectral functions. We discuss the implications of the in-medium properties of open-charm mesons on the Ds0(2317) and the predicted X(3700) scalar resonances.

Chaos in nuclei: Theory and experiment

During the last three decades the quest for chaos in nuclei has been quite intensive, both with theoretical calculations using nuclear models and with detailed analyses of experimental data. In this paper we outline the concept and characteristics of quantum chaos in two different approaches, the random matrix theory fluctuations and the time series fluctuations. Then we discuss the theoretical and experimental evidence of chaos in nuclei. Theoretical calculations, especially shell-model calculations, have shown a strongly chaotic behavior of bound states in regions of high level density. The analysis of experimental data has shown a strongly chaotic behavior of nuclear resonances just above the one-nucleon emission threshold. For bound states, combining experimental data of a large number of nuclei, a tendency towards chaotic motion is observed in spherical nuclei, while deformed nuclei exhibit a more regular behavior associated to the collective motion. On the other hand, it had never been possible to observe chaos in the experimental bound energy levels of any single nucleus. However, the complete experimental spectrum of the first 151 states up to excitation energies of 6.20 MeV in the 208Pb nucleus have been recently identified and the analysis of its spectral fluctuations clearly shows the existence of chaotic motion.

Nuclear medium effects on the K¯⁎ meson

The

bar K* meson in nuclear matter

\bar K^*

Nuclear medium effects on the

meson in dense matter is analyzed by means of a unitary approach in coupled channels based on the local hidden gauge formalism. The

\bar K^*

\bar K^*

meson

self-energy and the corresponding

K̄* meson in nuclear matter

\bar K^*