Minimal Measurable Length Research Articles

Inflationary universe in the presence of a minimal measurable length

In this paper, we will study the effect of having a minimum measurable length on inflationary cosmology. We will analyze the inflationary cosmology in the Jacobson approach. In this approach, gravity is viewed as an emergent thermodynamical phenomena. We will demonstrate that the existence of a minimum measurable length will modify the Friedmann equations in the Jacobson approach. We will use this modified Friedmann equation to analyze the effect of minimum measurable length scale on inflationary cosmology. This analysis will be performed using the Hamiltonian-Jacobi approach. We compare our results to recent data, and find that our model may agree with the recent data.

Some astrophysical aspects of a Schwarzschild geometry equipped with a minimal measurable length

By considering a deformation of the Schwarzschild metric in the presence of a minimal measurable length which still respects the equivalence principle, we study corrections to the standard general relativistic predictions for some astrophysical phenomena such as stability of circular orbits of black hole accretion disks, redshift of black hole accretion disks, gravitational tidal forces and the geodetic drift rate. We use the Gravity Probe B data to see robustness of our results. Our analysis shows also that the relevant deformation parameter ε which has a geometric origin, plays the same role as the charge to mass ratio, em in the Reissner–Nordström metric.

GUP-corrected thermodynamics of accelerating and rotating black holes

When quantum gravity effects, that are based on generalized uncertainty principle with a minimal measurable length, are incorporated into black hole physics the Klein–Gordon and Dirac equations get modified. Using these modified equations we investigate tunneling of scalar particles and fermions from event and acceleration horizons of accelerating and rotating black holes and obtain the modified Hawking temperature with quantum gravity effects. We see that Hawking temperature depends on black hole parameters as well as the quantum numbers of emitted fermions. The quantum corrections slow down black hole evaporation and leave a black hole remnant. This contradicts complete evaporation of a black hole which is presaged by the standard temperature formula for black holes. The modified Hawking temperatures presented here, in appropriate limits, are consistent with the previous results in the literature.

Short distance modification of the quantum virial theorem

In this letter, we will analyse the deformation of a semi-classical gravitational system from minimal measurable length scale. In the semi-classical approximation, the gravitational field will be analysed as a classical field, and the matter fields will be treated quantum mechanically. Thus, using this approximation, this system will be represented by a deformation of Schrödinger–Newton equation by the generalised uncertainty principle (GUP). We will analyse the effects of this GUP deformed Schrödinger–Newton equation on the behaviour of such a semi-classical gravitational system. As the quantum mechanical virial theorem can be obtained using the Schrödinger–Newton equation, a short distance modification of the Schrödinger–Newton equation will also result in a short distance modification of the quantum mechanical virial theorem.

Corrected black hole thermodynamics in Damour–Ruffini’s method with generalized uncertainty principle

Recently, some approaches to quantum gravity indicate that a minimal measurable length [Formula: see text] should be considered, a direct implication of the minimal measurable length is the generalized uncertainty principle (GUP). Taking the effect of GUP into account, Hawking radiation of massless scalar particles from a Schwarzschild black hole is investigated by the use of Damour–Ruffini’s method. The original Klein–Gordon equation is modified. It is obtained that the corrected Hawking temperature is related to the energy of emitting particles. Some discussions appear in the last section.

Thermal effects of a photon gas with a deformed Heisenberg algebra

In this paper, we have considered the thermodynamics of a photon gas subject to the presence of a minimal measurable length following from a covariant extension of the original generalized uncertainty principle (GUP). After consistently establishing a generalized dynamics, we define a GUP deformed Maxwell invariant which serves as the basis for our study. In order to highlight the GUP effects, we compute the one- and two-loop order contribution to the partition function at the high-temperature limit. Afterwards, by computing the internal energy density, we conclude that the additional terms can be seen as corrections [Formula: see text] to the Stefan–Boltzmann law due to GUP effects.

A note on coherent states with quantum gravity effects

Existence of a minimal measurable length and an upper bound for the momentum fluctuations are the casting reasons for generalization of uncertainty principle and then reformulation of Hilbert space representation of quantum mechanics. In this paper, we study the consequences of the Generalized Uncertainty Principle (GUP) in the presence of both minimal length and maximal momentum. We consider a simple harmonic oscillator in the framework of GUP by introducing its energy eigenstates and energy spectrum. Investigation of coherent states for a generalized harmonic oscillator and its generic behavior are the other topics in our study.

Lorentz invariance violation and generalized uncertainty principle

There are several theoretical indications that the quantum gravity approaches may have predictions for a minimal measurable length, and a maximal observable momentum and throughout a generalization for Heisenberg uncertainty principle. The generalized uncertainty principle (GUP) is based on a momentum-dependent modification in the standard dispersion relation which is conjectured to violate the principle of Lorentz invariance. From the resulting Hamiltonian, the velocity and time of flight of relativistic distant particles at Planck energy can be derived. A first comparison is made with recent observations for Hubble parameter in redshift-dependence in early-type galaxies. We find that LIV has two types of contributions to the time of flight delay $\Delta t$ comparable with that observations. Although the wrong OPERA measurement on faster-than-light muon neutrino anomaly, $\Delta t$, and the relative change in the speed of muon neutrino $\Delta v$ in dependence on redshift $z$ turn to be wrong, we utilize its main features to estimate $\Delta v$. Accordingly, the results could not be interpreted as LIV. A third comparison is made with the ultra high-energy cosmic rays (UHECR). It is found that an essential ingredient of the approach combining string theory, loop quantum gravity, black hole physics and doubly spacial relativity and the one assuming a perturbative departure from exact Lorentz invariance. Fixing the sensitivity factor and its energy dependence are essential inputs for a reliable confronting of our calculations to UHECR. The sensitivity factor is related to the special time of flight delay and the time structure of the signal. Furthermore, the upper and lower bounds to the parameter, $\alpha$ that characterizes the generalized uncertainly principle, have to be fixed in related physical systems such as the gamma rays bursts.

Bounds on quantum gravity parameter from the SU(2) NJL effective model of QCD

The existence of a minimal measurable length, as an effective cutoff in the ultraviolet regime, is a common feature of all approaches to the quantum gravity proposal. It is widely believed that this length scale will be of the order of the Planck length , where is a dimensionless parameter that should be fixed only by the experiments. This issue can be taken into account through the deformed momentum spaces with compact topologies. In this paper, we consider minimum length effects on the physical quantities related to three parameters of the SU(2) Nambu-Jona-Lasinio effective model of QCD by means of the deformed measure which is defined on the compact momentum space with S3 topology. This measure is suggested by the doubly special relativity theories, Snyder deformed spaces, and the deformed algebra that is obtained in the light of the stability theory of Lie algebras. Using the current experimental data of the particle physics collaboration, we constrain the quantum gravity parameter λ0 and we compare our results with bounds that are arisen from the other experimental setups.

Space tests of the generalized uncertainty principle

A generalized uncertainty principle admitting a minimal measurable length contains a parameter of which the numerical value needs to be fixed. In fact, the application of the Generalized Uncertainty Principle (GUP) to some quantum mechanical problems offers different values for the upper bound of the GUP dimensionless parameter \(\alpha_{0}\). In this work, by applying a GUP which is linear and quadratic in the \(\Delta P\) correction to Newton’s law of gravity, and then using the stability condition of the circular orbits of the planets, we propose an upper bound for \(\alpha_{0}\). By using the astronomical data of the Solar System objects, a new and severe constraint on the upper bound of the parameter \(\alpha_{0}\) is derived. Also, using the modified Newtonian potential, inspired by a GUP which is linear and quadratic in \(\Delta P\), we investigate the possibility of measuring the relevant parameter \(\alpha_{0}\) through observables provided by the Galileo Navigation Satellite System.

Effect of GUP on the Kepler problem and a variable minimal length

Various approaches to quantum gravity, such as string theory, predict a minimal measurable length and a modification of the Heisenberg uncertainty principle near the Plank scale, known as the generalized uncertainty principle (GUP). Here we study the effects of GUP, which preserves the rotational symmetry of the space–time, on the Kepler problem. By comparing the value of the perihelion shift of the planet Mercury in Schwarzschild – de Sitter space–time with the resultant value of GUP, we find a relation between the minimal measurable length and the cosmological constant of the space–time. Now, if the cosmological constant varies with time, we have a variable minimal length in the space–time. Finally, we investigate the effects of GUP on the stability of circular orbits.

MicroBlack Holes Thermodynamics in the Presence of Quantum Gravity Effects

Black hole thermodynamics is corrected in the presence of quantum gravity effects. Some phenomenological aspects of quantum gravity proposal can be addressed through generalized uncertainty principle (GUP) which provides a perturbation framework to perform required modifications of the black hole quantities. In this paper, we consider the effects of both a minimal measurable length and a maximal momentum on the thermodynamics of TeV-scale black holes. We then extend our study to the case that there are all natural cutoffs as minimal length, minimal momentum, and maximal momentum simultaneously. We also generalize our study to the model universes with large extra dimensions (LED). In this framework existence of black holes remnants as a possible candidate for dark matter is discussed. We study probability of black hole production in the Large Hadronic Collider (LHC) and we show this rate decreasing for sufficiently large values of the GUP parameter.

Thomas-Fermi Model in the Presence of Natural Cutoffs

It has been revealed, in the context of quantum gravity candidates, that measurement of position cannot be done with arbitrary precision and there is a finite resolution of space-time points. This leads naturally to a minimal measurable length of the order of Planck length. Also, in the context of newly proposed doubly special relativity theories, a test particle’s momentum cannot be arbitrarily imprecise leading nontrivially to a maximal momentum for a test particle. These two natural cutoffs affects most of quantum field theoretic arguments in the spirit of condensed matter physics. Here we focus on the role of these natural cutoffs on Thomas-Fermi theory in condensed matter physics. We show how quantum gravity effects can play important role phenomenologically in many-body interactions of solids.

COHERENT STATES IN GRAVITATIONAL QUANTUM MECHANICS

We present the coherent states of the harmonic oscillator in the framework of the generalized (gravitational) uncertainty principle (GUP). This form of GUP is consistent with various theories of quantum gravity such as string theory, loop quantum gravity and black-hole physics and implies a minimal measurable length. Using a recently proposed formally self-adjoint representation, we find the GUP-corrected Hamiltonian as a generator of the generalized Heisenberg algebra. Then following Klauder's approach, we construct exact coherent states and obtain the corresponding normalization coefficients, weight functions and probability distributions. We find the entropy of the system and show that it decreases in the presence of the minimal length. These results could shed light on possible detectable Planck-scale effects within recent experimental tests.

Formulation of Electrodynamics with an External Source in the Presence of a Minimal Measurable Length

In a series of papers,Quesne andTkachuk (2006) presented aD+ 1-dimensional (β,β)-two-parameter Lorentz-covariant deformed algebra which leads to a nonzero minimal measurable length. In this paper, the Lagrangian formulation of electrodynamics in a 3 + 1-dimensional spacetime described by Quesne-Tkachuk algebra is studied in the special case of β󸀠 = 2β up to the first order over the deformation parameter β. It is demonstrated that at the classical level there is a similarity between electrodynamics in the presence of a minimal measurable length (generalized electrodynamics) and Lee-Wick electrodynamics. We obtain the free space solutions of the inhomogeneous Maxwell’s equations in the presence of a minimal length. These solutions describe two vector particles (a massless vector particle and a massive vector particle). We estimate two different upper bounds on the isotropic minimal length. The first upper bound is near to the electroweak length scale (lelectroweak ∼ 10 −18 m), while the second one is near to the length scale for the strong interactions (lstrong ∼ 10 −15 m). The relationship between the Gaete-Spallucci nonlocal electrodynamics (2012) and electrodynamics with a minimal length is investigated.

Minimal length, maximal momentum, and Hilbert space representation of quantum mechanics

Kempf et al. in Ref. [1] have formulated a Hilbert space representation of quantum mechanics with a minimal measurable length. Recently it has been revealed, in the context of doubly special relativity, that a test particles' momentum cannot be arbitrarily imprecise and therefore there is an upper bound for momentum fluctuations. Taking this achievement into account, we generalize the seminal work of Kempf {\it et al.} to the case that there is also a maximal particles' momentum. Existence of an upper bound for the test particles' momentum provides several novel and interesting features, some of which are studied in this paper.

New approach to nonperturbative quantum mechanics with minimal length uncertainty

The existence of a minimal measurable length is a common feature of various approaches to quantum gravity such as string theory, loop quantum gravity and black-hole physics. In this scenario, all commutation relations are modified and the Heisenberg uncertainty principle is changed to the so-called Generalized (Gravitational) Uncertainty Principle (GUP). Here, we present a one-dimensional nonperturbative approach to quantum mechanics with minimal length uncertainty relation which implies X=x to all orders and P=p+(1/3)\beta p^3 to first order of GUP parameter \beta, where X and P are the generalized position and momentum operators and [x,p]=i\hbar. We show that this formalism is an equivalent representation of the seminal proposal by Kempf, Mangano, and Mann and predicts the same physics. However, this proposal reveals many significant aspects of the generalized uncertainty principle in a simple and comprehensive form and the existence of a maximal canonical momentum is manifest through this representation. The problems of the free particle and the harmonic oscillator are exactly solved in this GUP framework and the effects of GUP on the thermodynamics of these systems are also presented. Although X, P, and the Hamiltonian of the harmonic oscillator all are formally self-adjoint, the careful study of the domains of these operators shows that only the momentum operator remains self-adjoint in the presence of the minimal length uncertainty. We finally discuss the difficulties with the definition of potentials with infinitely sharp boundaries.

Quantization of Free Scalar Fields in the Presence of Natural Cutoffs

We construct a quantum theory of free scalar fields in (1+1)-dimensions based on the deformed Heisenberg algebrax^,p^=iħ1-βp+2β2p2, that admits the existence of both a minimal measurable length and a maximal momentum, whereβis a deformation parameter. We consider both canonical and path integral formalisms of the scenario. Finally a higher dimensional extension is easily performed in the path integral formalism.

Generalized Uncertainty Principle in the Presence of Extra Dimensions

We argue that in the generalized uncertainty principle (GUP) model, the parameter β0 whose square root, multiplied by Planck length ℓp, approximates the minimum measurable distance, varies with energy scales. Since the minimal measurable length and extra dimensions are both suggested by quantum gravity theories, we investigate the models based on the GUP and one extra dimension, compactified with radius ρ. We obtain an inspiring relation . This relation is also consistent with the predictions at Planck scale and the usual quantum mechanics scale. We also estimate the application range of the GUP model. It turns out that the minimum measurable length is exactly the compactification radius of the extra dimension.

Maximal acceleration, maximal angular velocity, and causal influence

The upper bounds to acceleration and angular velocity which are suggested by quantum gravitational effects are described, together with the relativistic bound to velocity, by means of a cone ℐ+ in the Lie algebra of the Poincare group. The connection between these bounds and the existence of a minimal measurable length (of the order of Planck's length) is illustrated by means of a simple model. The geometric properties of the cone ℐ+ and of other related structures are examined in some detail. The new geometric background requires some modifications of the concepts of causal influence and of spacetime coincidence, which are analyzed and shown to lead to some nonlocal features of the theory. Due to the smallness of Planck's length, these modifications to the causal relations cannot be observed by means of available experimental methods, but they could have some influence on the structure of elementary particles and on the very early cosmology.