46 research outputs found
Black holes production in self-complete quantum gravity
A regular black hole model, which has been proposed by Hayward, is
reconsidered in the framework of higher dimensional TeV unification and
self-complete quantum gravity scenario (Dvali, Spallucci). We point out the
"quantum" nature of these objects and compute their cross section production by
taking into account the key role played by the existence of a "minimal length"
l_0. We show as the threshold energy is related to l_0. We recover, in the high
energy limit, the standard "black-disk" form of the cross section, while it
vanishes, below threshold, faster than any power of the invariant mass-energy
\sqrt{-s}.Comment: 12 pages; 3 figures; accepted for publication in PL
Thermodynamical phases of a regular SAdS black hole
This paper studies the thermodynamical stability of regular BHs in AdS5
background. We investigate off-shell free energy of the system as a function of
temperature for different values of a "coupling constant" L=4 theta/l^2, where
the cosmological constant is Lambda = -3/l^2 and \sqrt{theta} is a "minimal
length". The parameter L admits a critical value, L_{inf}=0.2, corresponding to
the appearance of an inflexion point in the Hawking temperature. In the
weak-coupling regime L < L_{inf}, there are first order phase transitions at
different temperatures. Unlike the Hawking-Page case, at temperature 0\le T \le
T_{min} the ground state is populated by "cold" near-extremal BHs instead of a
pure radiation. On the other hand, for L \g L_{inf} only large,
thermodynamically stable, BHs exist.Comment: 12 pages; 6 Figures; accepted for publication in Int. J. Mod. Phys.
Maxwell's equal area law and the Hawking-Page phase transition
In this paper we study the phases of a Schwarzschild black hole in the Anti
deSitter background geometry. Exploiting fluid/gravity duality we construct the
Maxwell equal area isotherm T=T* in the temperature-entropy plane, in order to
eliminate negative heat capacity black hole configurations. The construction we
present here is reminiscent of the isobar cut in the pressure-volume plane
which eliminates un-physical part of the Van der Walls curves below the
critical temperature. Our construction also modifies the Hawking-Page phase
transition. Stable black holes are formed at the temperature T > T*, while pure
radiation persists for T< T*. T* turns out to be below the standard
Hawking-Page temperature and there are no unstable black holes as in the usual
scenario. Also, we show that in order to reproduce the correct black hole
entropy S=A/4, one has to write a black hole equation of state, i.e. P=P(V), in
terms of the geometrical volume V=4\pi r^3/3.Comment: 15 pages, 4 Figures. Accepted for publication in Journal of Gravit
Dynamically self-regular quantum harmonic black holes
The recently proposed UV self-complete quantum gravity program is a new and
very interesting way to envision Planckian/trans-Planckian physics. in this new
framework, high energy scattering is dominated by the creation of micro black
holes, and it is experimentally impossible to probe distances shorter than the
horizon radius. In this letter we present a model which realizes this idea
through the creation of self-regular quantum black holes admitting a minimal
size extremal configuration. Their radius provides a dynamically generated
minimal length acting as a universal short-distance cut-off. We propose a
quantisation scheme for this new kind of microscopic objects based on a
Bohr-like approach, which does not require a detailed knowledge of quantum
gravity. The resulting black hole quantum picture resembles the energy spectrum
of a quantum harmonic oscillator. The mass of the extremal configuration plays
the role of zero-point energy. Large quantum number re-establish the classical
black hole description. Finally, we also formulate a "quantum hoop conjecture"
which is satisfied by all the mass eigen-states and sustains the existence of
quantum black holes sourced by Gaussian matter distributions.Comment: 14 pages; 2 Figures. In print in Physics Letters
A particle-like description of Planckian black holes
In this paper we abandon the idea that even a "quantum" black hole, of Planck size, can still be described as a classical, more or less complicated, geometry. Rather, we consider a genuine quantum mechanical approach where a Planckian black hole is, by all means, just another "particle", even if with a distinguishing property: its linear size increases with the energy. The horizon dynamics is equivalently described in terms of a particle moving in gravitational potential derived from the horizon equation itself in a self-consistent manner. The particle turning-points match the radius of the inner and outer horizons of a charged black hole. This classical model pave the way towards the wave equation for a truly quantum black hole. We compute the exact form of the wave function and determine the energy spectrum. Finally, we describe the classical limit in which the quantum picture correctly approaches the classical geometric formulation. We find that the quantum-to-classical transition occurs far above the Planck scale