Bulletin of the American Physical Society
2008 Annual Meeting of the Division of Nuclear Physics
Volume 53, Number 12
Thursday–Sunday, October 23–26, 2008; Oakland, California
Session GA: Quantum Phase Transitions in Atomic Nuclei and Other Finite Fermi Systems |
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Chair: Richard Casten, Yale University Room: Simmons Ballroom 2-3 |
Saturday, October 25, 2008 10:30AM - 11:06AM |
GA.00001: Emergence of regularities and symmetries from complex nuclei Invited Speaker: A challenge in studying complex many-body systems is to understand the remarkable regularities they sometimes exhibit and possibly relate these to the underlying symmetry of the system. Progress in this direction was initiated by the discovery of particular nuclei that undergo quantum phase transitions in their equilibrium shapes and the development of extremely simple, analytic descriptions of nuclei at the phase transitional point in terms of critical point symmetries (CPS). Recent results inspired by the concept of CPS will be presented. Experiments aimed at identifying empirical manifestations of CPS, previously constrained to a few select regions, will be presented, covering a wider range of the nuclear chart. New observables will be discussed which not only serve as effective order parameters for identifying phase transitional behavior, but also distinguish between first and second order phase transitions. Finally, very simple and general regularities in the predictions of not only CPS, but also in other standard models, will be presented. These suggest the presence of possible underlying symmetries in a wider range of structures not limited to the critical point. This research is supported by the DOE Office of Nuclear Physics under contract DE-AC02-06CH11357. [Preview Abstract] |
Saturday, October 25, 2008 11:06AM - 11:42AM |
GA.00002: Probing Quantum Phase Changes in Nuclear Reactions Invited Speaker: Strong indications of a phase change analogous to the classical liquid gas phase transition have been observed in nuclear collisions. However the analogy should not be overstressed as nuclear matter is a strongly interacting quantum system. In the nuclear case the difference between the neutron and proton concentrations acts as an additional order parameter for which the symmetry potential is the conjugate variable. We present experimental data revealing the N/Z dependence of the nuclear phase transition and discuss possible implications in terms of the Landau Free Energy description of critical phenomena.\footnote{A. Bonasera et al, submitted to Phys. Rev. Lett, 2008} At very low densities the clustered state is more stable than uniform matter and theoretical calculations indicate the existence of Bose Condensates and possibly self-bound boselets or fermilets owing their existence to three-body bound states, the Efimov effect. Evidence for such behavior is also being sought in collision studies. [Preview Abstract] |
Saturday, October 25, 2008 11:42AM - 12:18PM |
GA.00003: Thermodynamic properties and phase transitions in dilute fermion matter Invited Speaker: If the average interparticle distance between fermions exceeds considerably the radius of the interaction, and if the scattering length is larger than the average interparticle separation, the properties of such fermion matter become universal. Under such conditions low density neutron matter has essentially identical properties to cold atoms in traps. While the properties of such low density neutron matter cannot be studied in the lab yet, that is not the case for cold atoms. This system shares also a number of properties with the high density phase of QCD, when quarks are deconfined. From the theoretical point of view the dilute fermion system is particularly attractive, as in many cases one can aim at a full and rather accurate solution of the Schr\"{o}dinger equation either for the ground state or at finite temperatures, using~Quantum Monte Carlo (QMC)~and Density Functional Theory (DFT) techniques. This field became a beloved playing ground for many-body theorists, since many old and new techniques can be accurately validated against exact results and verified against accurate measurements. I shall present an overview of our current status of the theory, in particular what we have learned so far using QMC and DFT techniques both at zero and finite temperature, discuss the surprisingly rich phase diagram of such matter and the relevance of this new knowledge to nuclear physics and astrophysics. [Preview Abstract] |
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