相关论文: Thermodynamics of k-essence

We extend previous work showing that violation of the null energy condition implies instability in a broad class of models, including gauge theories with scalar and fermionic matter as well as any perfect fluid. Simple examples are given to…

Well known results in string thermodynamics show that there is always a negative specific heat phase in the microcanonical description of a gas of closed free strings whenever there are no winding modes present. We will carefully compute…

Dark energy is usually parametrized as a perfect fluid with negative pressure and a certain equation of state. Besides, it is supposed to interact very weakly with the rest of the components of the universe and, as a consequence, there is…

In spherical symmetry, the gravitational potential is uniquely determined by the rotational velocity profile. Numerous galaxies exhibit a universal velocity profile from which a universal gravitational profile is inferred. When treating…

This paper deals with the thermodynamical properties of black hole formulated in Einstein theory of relativity and associated with a nonlinear electromagnetic field. The transition of the black hole is analyzed using the parameters mass,…

Our aim is studying the thermodynamics of cosmological models including initial and final de-Sitter eras. For this propose, bearing Cai-Kim temperature in mind, we investigate the thermodynamic properties of a dark energy candidate with…

Adopting the thin-layer improved brick-wall method, we investigate the thermodynamics of a black hole embedded in a spatially flat Friedmann-Robertson-Walker universe. We calculate the temperature and the entropy at every apparent horizon…

Black holes are thermodynamic objects, but despite recent progress, the ultimate statistical mechanical origin of black hole temperature and entropy remains mysterious. Here I summarize an approach in which the entropy is viewed as arising…

We investigated the thermodynamic properties of graphene in a noncommutative phase-space in the presence of a constant magnetic field. In particular, we determined the behaviour of the main thermodynamical functions: the Helmholtz free…

In this brief review, we examine the theoretical consistency and viability of phantom dark energy. Almost all data sets from cosmological probes are compatible with dark energy of the phantom variety (i.e., equation-of-state parameter…

We show that, in the context of the two-field measure theory, any k-essence model leads to the existence of a fluid made of non-relativistic matter and cosmological constant that would explain the dark matter and dark energy problem at the…

Thermal duality, which relates the physics of closed strings at temperature T to the physics at the inverse temperature 1/T, is one of the most intriguing features of string thermodynamics. Unfortunately, the classical definitions of…

Black hole thermodynamics is the area of study that seeks to reconcile the laws of thermodynamics with the existence of black hole event horizons. Here we calculate the entropy corresponding to the interior of a Schwarzschild black hole for…

We consider a substance with equation of state $P=wE$ at constant $w$ and find that it is an ideal gas of quasi-particles with the energy spectrum $\epsilon_p\sim p^{wq}$ that can constitute either regular matter (when $w>0$) or exotic…

For extremal charged black holes, the thermodynamic entropy is proportional not to the area but to the mass or charges. This is demonstrated here for dyonic extremal black hole solutions of string theory. It is pointed out that these…

In spite of its rather weird properties which include violation of the dominant-energy condition, the requirement of superluminal sound speed and increasing vacuum-energy density, phantom energy has recently attracted a lot of scientific…

We discuss and compare different definitions of the entropy of a black hole. In particular we show that the thermodynamical entropy defined by the response of the free energy of a black hole to the change of temperature does not coincide…

We have analytically explored thermodynamics of free Bose and Fermi gases for the entire range of temperature, and have extended the same for harmonically trapped cases. We have obtained approximate chemical potentials of the quantum gases…

It is well known that, in the context of general relativity, an unknown kind of matter that must violate the strong energy condition is required to explain the current accelerated phase of expansion of the Universe. This unknown component…

The existence of inequivalent representations in quantum field theory with {\it finitely} many degrees of freedom is shown. Their properties are exemplified and analysed for concrete and simple models. In particular the relations to…