2,175 research outputs found
Lorentz violation and generalized uncertainty principle
Full text linkInvestigations on possible violation of Lorentz invariance have been widely pursued in the last decades,
both from theoretical and experimental sides. A comprehensive framework to formulate the problem is the
standard model extension (SME) proposed by A. Kostelecky, where violation of Lorentz invariance is
encoded into specific coefficients. Here we present a procedure to link the deformation parameter β of the
generalized uncertainty principle to the SME coefficients of the gravity sector. The idea is to compute the
Hawking temperature of a black hole in two different ways. The first way involves the deformation
parameter β, and therefore we get a deformed Hawking temperature containing the parameter β. The second
way involves a deformed Schwarzschild metric containing the Lorentz violating terms ̄sμν of the gravity
sector of the SME. The comparison between the two different techniques yields a relation between β and
̄sμν. In this way bounds on β transferred from ̄sμν are improved by many orders of magnitude when
compared with those derived in other gravitational frameworks. Also the opposite possibility of bounds
transferred from β to ̄sμν is briefly discussed
Planck Stars from a Scale-dependent Gravity theory
Full text linkScale dependence of fundamental physical parameters is a generic feature of
ordinary quantum field theory. When applied to gravity, this idea produces
effective actions generically containing a running Newtonian coupling constant,
from which new (spherically symmetric) black hole spacetimes can be inferred.
As a minimum useful requirement, of course, the new metrics should match with a
Schwarzschild field at large radial coordinate. By further imposing to the new
scale dependent metric the simple request of matching with the Donoghue quantum
corrected potential, we find a not yet explored black hole spacetime, which
naturally turns out to describe the so-called Planck stars.Comment: 15 pages, 3 figures. Final version, to appear in Physical Review
Uncertainty relations and precession of perihelion
No full textWe compute the corrections to the Schwarzschild metric necessary to reproduce the Hawking temperature derived from a Generalized Uncertainty Principle (GUP), so that the GUP deformation parameter is directly linked to the deformation of the metric. Using this modified Schwarzschild metric, we compute corrections to the standard General Relativistic predictions for the perihelion precession for planets in the solar system, and for binary pulsars. This analysis allows us to set bounds for the GUP deformation parameter from well-known astronomical measurements
Generalized Uncertainty Principle, Classical Mechanics, and General Relativity
Full text linkThe Generalized Uncertainty Principle (GUP) has been directly applied to the motion of (macroscopic) test bodies on a given space-time in order to compute corrections to the classical orbits predicted in Newtonian Mechanics or General Relativity. These corrections generically violate the Equivalence Principle. The GUP has also been indirectly applied to the gravitational source by relating the GUP modified Hawking temperature to a deformation of the background metric. Such a deformed background metric determines new geodesic motions without violating the Equivalence Principle. We point out here that the two effects are mutually exclusive when compared with experimental bounds. Moreover, the former stems from modified Poisson brackets obtained from a wrong classical limit of the deformed canonical commutators
Generalized uncertainty principle, extra dimensions and holography
No full textWe consider uncertainty principles which take into account the role of gravity and the possible existence of extra spatial dimensions. Explicit expressions for such generalized uncertainty principles in 4 + n dimensions are given and their holographic properties investigated. In particular, we show that the predicted number of degrees of freedom enclosed in a given spatial volume matches the holographic counting only for one of the available generalizations and without extra dimensions
A metric for Planck Stars derived from Gravity in Asymptotic Safety
No full textThe Asymptotically Safe Gravity (ASG) framework suggests a "running"Newtonian coupling constant, which depends on two free parameters ω and γ. The new black hole metrics inferred from such a "running"gravitational constant naturally match with a Schwarzschild metric at large radial coordinate. By further imposing the matching with the Donoghue quantum corrections to the Schwarzschild field, we find a negative value of the ω∼ parameter, and this leads to a not yet explored black hole metric, which surprisingly turns out to describe the so-called Planck stars
Quantum hoop conjecture: Black hole formation by particle collisions
No full textAbstractWe address the issue of (quantum) black hole formation by particle collision in quantum physics. We start by constructing the horizon wave-function for quantum mechanical states representing two highly boosted non-interacting particles that collide in flat one-dimensional space. From this wave-function, we then derive a probability that the system becomes a black hole as a function of the initial momenta and spatial separation between the particles. This probability allows us to extend the hoop conjecture to quantum mechanics and estimate corrections to its classical counterpart
Horizon wave function for single localized particles: GUP and quantum black-hole decay
Full text linkA localized particle in Quantum Mechanics is described by a wave packet in position space, regardless of its energy. However, from the point of view of General Rela- tivity, if the particle’s energy density exceeds a certain thresh- old, it should be a black hole. To combine these two pictures, we introduce a horizon wave function determined by the par- ticle wave function in position space, which eventually yields the probability that the particle is a black hole. The existence of a minimum mass for black holes naturally follows, albeit not in the form of a sharp value around the Planck scale, but rather like a vanishing probability that a particle much lighter than the Planck mass may be a black hole. We also show that our construction entails an effective generalized uncertainty principle (GUP), simply obtained by adding the uncertainties coming from the two wave functions associated with a parti- cle. Finally, the decay of microscopic (quantum) black holes is also described in agreement with what the GUP predicts
Generalized uncertainty principle, extra-dimensions and holography
No full textWe consider Uncertainty Principles which take into account the role of gravity and the possible existence of extra spatial dimensions. Explicit expressions for such Generalized Uncertainty Principles in 4+n dimensions are given and their holographic properties investigated. In particular, we show that the predicted number of degrees of freedom enclosed in a given spatial volume matches the holographic counting only for one of the available generalizations and without extra dimensions
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