arXiv subjects

Jacek Dobaczewski

Publications and source records attributed to Jacek Dobaczewski.

23 records · Page 2Linked to original sources

arXiv2009

On Th229 and time-dependent fundamental constants

The electromagnetic transition between the almost degenerate 5/2+ and 3/2+ states in Th229 is deemed to be very sensitive to potential changes in the fine structure constant alpha. State of the art Hartree-Fock and Hartree-Fock-Bogoliubov calculations are performed to compute the difference in Coulomb energies of the two states which determines the amplification of variations in alpha into variations of the transition frequency. The kinetic energies are also calculated which reflect a possible variation in the nucleon or quark masses. A generalized Hellmann-Feynman theorem is proved including the use of density-matrix functionals. As the two states differ mainly in the orbit occupied by the last unpaired neutron the Coulomb energy difference results from a change in the nuclear polarization of the proton distribution. This effect turns out to be rather small and to depend on the nuclear model, the amplification varies between about -4 x 10^4 and +4 x 10^4. Therefore much more effort must be put into the improvement of the nuclear models before one can draw conclusions from a measured drift in the transition frequency on a temporal drift of fundamental constants. All calculations published so far do not reach the necessary fidelity. PACS 06.20.Jr,21.60.Jz,27.90.+b

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arXiv2009

Hartree-Fock-Bogoliubov Theory of Polarized Fermi Systems

Condensed Fermi systems with an odd number of particles can be described by means of polarizing external fields having a time-odd character. We illustrate how this works for Fermi gases and atomic nuclei treated by density functional theory or Hartree-Fock-Bogoliubov (HFB) theory. We discuss the method based on introducing two chemical potentials for different superfluid components, whereby one may change the particle-number parity of the underlying quasiparticle vacuum. Formally, this method is a variant of non-collective cranking, and the procedure is equivalent to the so-called blocking. We present and exemplify relations between the two-chemical-potential method and the cranking approximation for Fermi gases and nuclei.

cond-mat.supr-con↗

arXiv2002

Theoretical developments in heavy nuclei

The present-day nuclear structure theory exhibits a great degree of synergy with respect to methods that are used to describe various phenomena in heavy nuclear systems. From few-body methods, through the shell model to mean-field approaches, the bridges are being built between different ways of describing the stable as well as the most exotic nuclei. In the present talk, I give a review of several selected subjects that are currently at the fore front of new developments in this domain of nuclear science.

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arXiv2002

Mean-Field and Pairing Properties of Exotic Nuclei: Exploring the Nuclear Landscape

In years to come, we shall see substantial progress in our understanding of nuclear structure - a rich and many-faceted field. An important element in this task will be to extend the study of nuclei into new domains. The journey to 'the limits' of isospin, angular momentum, and mass and charge is a quest for new and unexpected phenomena which await us in uncharted territories. What is extremely important from a theoretical point of view is that the new data are also expected to bring qualitatively new information about the effective nucleon-nucleon interaction and hence about the fundamental properties of the nucleonic many-body system. The main objective of this presentation is to discuss some of the challenges and opportunities for nuclear structure research with radioactive nuclear beams.

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arXiv1997

Theoretical Aspects of Science with Radioactive Nuclear Beams

Physics of radioactive nuclear beams is one of the main frontiers of nuclear science today. Experimentally, thanks to technological developments, we are on the verge of invading the territory of extreme N/Z ratios in an unprecedented way. Theoretically, nuclear exotica represent a formidable challenge for the nuclear many-body theories and their power to predict nuclear properties in nuclear terra incognita. It is important to remember that the lesson learned by going to the limits of the nuclear binding is also important for normal nuclei from the neighborhood of the beta stability valley. And, of course, radioactive nuclei are crucial astrophysically; they pave the highway along which the nuclear material is transported up in the proton and neutron numbers during the complicated synthesis process in stars.

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