Aspects quantiques et dissipatifs dans la structure et la dynamique nucléaires

Abstract : This work is devoted to the description of both quantal and statistical aspects in a coherent theoretical framework that goes beyond a mean-field approximation. It is shown that among the possible methods, the Extended mean-field theory (ETDHF) is able to describe relaxation by including correlation effects. This theory is first applied to cold and hot giant resonances. After having developed a extended version of the linear response theory the effect of collisions on the response of 40Ca is studied. It is shown that collisions contribute to the spreading width of giant resonances and become a dominant decay channel at high temperature. The generalization of these methods through the modelization of the Hamiltonian as a series of couplings in cascade has enabled to go beyond ETDHF. Thus, phenomena as multi-scale Ericson fluctuations and interferences in the nuclear response are predicted. The study of larger amplitudes requires the introduction of transport theories for the nuclear dynamics. Thus the deexcitation of hot and compressed nuclei has been studied with mean-field theories. This analysis has clarified the link between the equation of state and the dynamical expansion in finite Systems. A comparison with semi-classical has further shown the importance of quantum effects and has demonstrated the necessity to take into account nucleon collisions in a quantum framework. The possibility to apply ETDHF to nuclear dynamics in the general case is then discussed. A rapid and reliable method, tested on a schematic model is proposed to solve the extended mean-field. The application of ETDHF to the monopolar expansion of 16O has finally demonstrated the interesting perspectives of this theory for describing dissipative aspects in quantum dynamics. Finally, the introduction of quantum stochastic approaches is discussed.
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Submitted on : Wednesday, October 5, 2016 - 10:19:59 AM
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D. Lacroix. Aspects quantiques et dissipatifs dans la structure et la dynamique nucléaires. Physique Nucléaire Théorique [nucl-th]. Université de Caen, 1999. Français. ⟨in2p3-00015141⟩

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