Out-of-equilibrium phase re-entrance(s) in long-range interacting systems

Journal Article · Sat Aug 15 00:00:00 EDT 2009 · Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics (Print)

DOI:https://doi.org/10.1103/PHYSREVE.80.021138· OSTI ID:21344686

Staniscia, F ^[1]; Chavanis, P H ^[2]; De Ninno, G ^[3]; Fanelli, D ^[4]

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1. Dipartimento di Fisica, Universita di Trieste, 34127 Trieste (Italy)
2. Laboratoire de Physique Theorique (IRSAMC), Universite de Toulouse, UPS, F-31062 Toulouse (France)
3. Sincrotrone Trieste, S.S. 14 km 163.5, Basovizza, 34149 Trieste (Italy)
4. Dipartimento di Energetica 'Sergio Stecco', Universita di Firenze, via S. Marta 3, 50139 Firenze (Italy)

Systems with long-range interactions display a short-time relaxation toward quasistationary states (QSSs) whose lifetime increases with system size. The application of Lynden-Bell's theory of 'violent relaxation' to the Hamiltonian Mean Field model leads to the prediction of out-of-equilibrium first- and second-order phase transitions between homogeneous (zero magnetization) and inhomogeneous (nonzero magnetization) QSSs, as well as an interesting phenomenon of phase re-entrances. We compare these theoretical predictions with direct N-body numerical simulations. We confirm the existence of phase re-entrance in the typical parameter range predicted from Lynden-Bell's theory, but also show that the picture is more complicated than initially thought. In particular, we exhibit the existence of secondary re-entrant phases: we find unmagnetized states in the theoretically magnetized region as well as persisting magnetized states in the theoretically unmagnetized region. We also report the existence of a region with negative specific heats for QSSs both in the numerical and analytical caloric curves.

• OSTI ID: 21344686
• Journal Information: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics (Print), Vol. 80, Issue 2; Other Information: DOI: 10.1103/PhysRevE.80.021138; (c) 2009 The American Physical Society; ISSN 1539-3755
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMPUTERIZED SIMULATION
HAMILTONIANS
INTERACTION RANGE
LIFETIME
MAGNETIZATION
MANY-BODY PROBLEM
MEAN-FIELD THEORY
ORDER-DISORDER TRANSFORMATIONS
RELAXATION
SPECIFIC HEAT
STATISTICAL MECHANICS
THERMODYNAMICS
DISTANCE
MATHEMATICAL OPERATORS
MECHANICS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
QUANTUM OPERATORS
SIMULATION
THERMODYNAMIC PROPERTIES