208 research outputs found
Quantum phase transitions in Bose-Fermi systems
Quantum phase transitions in a system of N bosons with angular momentum L=0,2
(s,d) and a single fermion with angular momentum j are investigated both
classically and quantum mechanically. It is shown that the presence of the odd
fermion strongly influences the location and nature of the phase transition,
especially the critical value of the control parameter at which the phase
transition occurs. Experimental evidence for the U(5)-SU(3) (spherical to
axially-deformed) transition in odd-even nuclei is presented.Comment: 38 pages, 29 figure
Partial Dynamical Symmetry at Critical-Points of Quantum Phase Transitions
We show that partial dynamical symmetries (PDS) can occur at critical-points
of quantum phase transitions, in which case, underlying competing symmetries
are conserved exactly by a subset of states, and mix strongly in other states.
Several types of PDS are demonstrated with the example of critical-point
Hamiltonians for first- and second-order transitions in the framework of the
interacting boson model, whose dynamical symmetries correspond to different
shape-phases in nuclei.Comment: 4 pages, 5 figures, minor adjustments to PRL requirements. PRL in
pres
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