RT Journal Article
T1 Phase diagram of the two-fluid Lipkin model : a "butterfly" catastrophe
A1 García Ramos, José Enrique
A1 Pérez Fernández, Pedro
A1 Arias Carrasco, José Miguel
A1 Freire, Emilio
AB Background: In the last few decades quantum phase transitions have been of great interest in Nuclear Physics. In this context, two-fluid algebraic models are ideal systems to study how the concept of quantum phase transition evolves when moving into more complex systems, but the number of publications along this line has been scarce up to now. Purpose: We intend to determine the phase diagram of a two-fluid Lipkin model, that resembles the nuclear proton-neutron interacting boson model Hamiltonian, using both numerical results and analytic tools, i.e., catastrophe theory, and to compare the mean-field results with exact diagonalizations for large systems.Method: The mean-field energy surface of a consistent-Q-like two-fluid Lipkin Hamiltonian is studied and compared with exact results coming from a direct diagonalization. The mean-field results are analyzed using the framework of catastrophe theory.   Results: The phase diagram of the model is obtained and the order of the different phase-transition lines and surfaces is determined using a catastrophe theory analysis.  Conclusions: There are two first order surfaces in the phase diagram, one separating the spherical and the deformed shapes, while the other separates two different deformed phases. A second order line, where the later surfaces merge, is found. This line finishes in a transition point with a divergence in the second order derivative of the energy that corresponds to a tricritical point in the language of the Ginzburg-Landau theory for phase transitions.
PB American Physical Society
SN 0556-2813
SN 1089-490X (electrónico)
YR 2016
FD 2016
LK http://hdl.handle.net/10272/11792
UL http://hdl.handle.net/10272/11792
LA eng
NO García Ramos, J.R., Pérez Fernández, P., Arias Carrasco, J.M., Freire, E.: "Phase diagram of the two-fluid Lipkin model : a “butterfly” catastrophe". Physical Review C. Vol. 93, 034336, (2016). DOI: 10.1103/PhysRevC.93.034336
NO This work has been supported by Ministerio de Economia y Competitividad (Spain) and the European Regional Development Fund (FEDER) under projects FIS2014-53448-C2-1-P, and FIS2014-53448-C2-2-P, and by Consejeria de Economia, Innovacion, Ciencia y Empleo de la Junta de Andalucia (Spain) under Group FQM-160, TIC130, and FQM370.
DS Repositorio Institucional de la Universidad de Huelva
RD 2 jun 2026