53,775 research outputs found
Critical phenomena of static charged AdS black holes in conformal gravity
The extended thermodynamics of static charged AdS black holes in conformal
gravity is analyzed. The criticality of these black holes has some
unusual features. There exists a single critical point with critical
temperature and critical pressure . At fixed (or at fixed
), there are two zeroth order phase transition points but no first order
phase transition points. The systems favors large pressure states at constant
, or high temperature states at constant .Comment: 16 pages, 3 figures; published versio
Landau meets Newton: time translation symmetry breaking in classical mechanics
Every classical Newtonian mechanical system can be equipped with a
nonstandard Hamiltonian structure, in which the Hamiltonian is the square of
the canonical Hamiltonian up to a constant shift, and the Poisson bracket is
nonlinear. In such a formalism, time translation symmetry can be spontaneously
broken, provided the potential function becomes negative. A nice analogy
between time translation symmetry breaking and the Landau theory of second
order phase transitions is established, together with several example cases
illustrating time translation breaking ground states. In particular, the
CDM model of FRW cosmology is reformulated as the time translation
symmetry breaking ground states.Comment: 10 pages, 1 figure. V2: minor correction
Extended phase space thermodynamics for third order Lovelock black holes in diverse dimensions
Treating the cosmological constant as thermodynamic pressure and its
conjugate as thermodynamic volume, we investigate the critical behavior of the
third order Lovelock black holes in diverse dimensions. For black hole horizons
with different normalized sectional curvature , the corresponding
critical behaviors differ drastically. For , there is no critical point in
the extended thermodynamic phase space. For , there is a single critical
point in any dimension , and for , there is a single critical
point in dimension and two critical points in dimensions. We
studied the corresponding phase structures in all possible cases.Comment: pdflatex, 22 pages, 36 eps figures included. V2: minor corrections
and new reference
Gauss-Bonnet coupling constant as a free thermodynamical variable and the associated criticality
The thermodynamic phase space of Gauss-Bonnet (GB) AdS black holes is
extended, taking the inverse of the GB coupling constant as a new thermodynamic
pressure . We studied the critical behavior associated with
in the extended thermodynamic phase space at fixed
cosmological constant and electric charge. The result shows that when the black
holes are neutral, the associated critical points can only exist in five
dimensional GB-AdS black holes with spherical topology, and the corresponding
critical exponents are identical to those for Van der Waals system. For charged
GB-AdS black holes, it is shown that there can be only one critical point in
five dimensions (for black holes with either spherical or hyperbolic
topologies), which also requires the electric charge to be bounded within some
appropriate range; while in dimensions, there can be up to two different
critical points at the same electric charge, and the phase transition can occur
only at temperatures which are not in between the two critical values.Comment: 23 pages. V2: modified all P_{GB}-r_+ plots using dimensionless
variables, added comments on the relationship to Einstein limi
Thermodynamics of pairing transition in hot nuclei
The pairing correlations in hot nuclei Dy are investigated in terms
of the thermodynamical properties by covariant density functional theory. The
heat capacities are evaluated in the canonical ensemble theory and the
paring correlations are treated by a shell-model-like approach, in which the
particle number is conserved exactly. A S-shaped heat capacity curve, which
agrees qualitatively with the experimental data, has been obtained and analyzed
in details. It is found that the one-pair-broken states play crucial roles in
the appearance of the S shape of the heat capacity curve. Moreover, due to the
effect of the particle-number conservation, the pairing gap varies smoothly
with the temperature, which indicates a gradual transition from the superfluid
to the normal state.Comment: 13 pages, 4 figure
Novel accelerating Einstein vacua and smooth inhomogeneous Riemannian manifolds
A novel class of Einstein vacua is presented, which possess non-vanishing
cosmological constant and accelerating horizon with the topology of
fibration over . After Euclideanization, the solution describes a
conformally distorted fibration over , which is smooth, compact
and inhomogeneous, and can be regarded as analogue of Don Page's gravitational
instanton.Comment: 14 pages. v2: Reference adde
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