311 research outputs found
Generalized Uncertainty Principle and the Ramsauer-Townsend Effect
The scattering cross section of electrons in noble gas atoms exhibits a
minimum value at electron energies of approximately 1eV. This is the
Ramsauer-Townsend effect. In this letter, we study the Ramsauer-Townsend effect
in the framework of the Generalized Uncertainty Principle.Comment: 11 pages, 3 figure
Loop Quantum Gravity Modification of the Compton Effect
Modified dispersion relations(MDRs) as a manifestation of Lorentz invariance
violation, have been appeared in alternative approaches to quantum gravity
problem. Loop quantum gravity is one of these approaches which evidently
requires modification of dispersion relations. These MDRs will affect the usual
formulation of the Compton effect. The purpose of this paper is to incorporate
the effects of loop quantum gravity MDRs on the formulation of Compton
scattering. Using limitations imposed on MDRs parameters from Ultra High Energy
Cosmic Rays(UHECR), we estimate the quantum gravity-induced wavelength shift of
scattered photons in a typical Compton process. Possible experimental detection
of this wavelength shift will provide strong support for underlying quantum
gravity proposal.Comment: 12 pages, 2 eps figures, revised versio
Effects of the Generalized Uncertainty Principle on the Inflation Parameters
We investigate the effects of the generalized uncertainty principle on the
inflationary dynamics of the early universe in both standard and braneworld
viewpoint. We choose the Randall-Sundrum II model as our underlying braneworld
scenario. We find that the quantum gravitational effects lead to a spectral
index which is not scale invariant. Also, the amplitude of density fluctuations
is reduced by increasing the strength of quantum gravitational corrections.
However, the tensor-to-scalar ratio increases by incorporation of these quantum
gravity effects. We outline possible manifestations of these quantum gravity
effects in the recent and future observations.Comment: 11 pages, revised version with new references, Accepted for
publication in IJMP
Entropic force approach in a noncommutative charged black hole and the equivalence principle
Recently, Verlinde has suggested a novel model of duality between
thermodynamics and gravity which leads to an emergent phenomenon for the origin
of gravity and general relativity. In this paper, we investigate some features
of this model in the presence of noncommutative charged black hole by
performing the method of coordinate coherent states representing smeared
structures. We derive several quantities, e.g. temperature, energy and entropic
force. Our approach clearly exhibits that the entropic force on a smallest
fundamental cell of holographic surface with radius is halted.
Accordingly, we can conclude that the black hole remnants are absolutely inert
without gravitational interactions. So, the equivalence principle of general
relativity is contravened due to the fact that it is now possible to find a
difference between the gravitational and inertial mass. In other words, the
gravitational mass in the remnant size does not emit any gravitational field,
therefore it is experienced to be zero, contrary to the inertial mass. This
phenomenon illustrates a good example for a feasible experimental confirmation
to the entropic picture of Newton's Second law in very short distances.Comment: 11 pages, 2 figure
Cosmological LTB Black Hole in a Quintom Universe
We study cosmological Lemaitre-Tolman-Bondi (LTB) black hole thermodynamics
immersed in a quintom universe. We investigate some thermodynamic aspects of
such a black hole in detail. We apply two methods of treating particles'
tunneling from the apparent horizons and calculate the black hole's temperature
in each method; the results of which are the same. In addition, by considering
specific time slices in cosmic history, we study the thermodynamic features of
this black hole in these specific cosmic epochs. Also, we discuss the
information loss problem and the remnant content of the cosmological black hole
in different cosmic epochs in this context. We show that approximately in all
cosmic history, the temperature of the black hole's apparent horizon is more
than the temperature of the cosmological apparent horizon
Did I say dog or cat? A study of semantic error detection and correction in children
Although naturalistic studies of spontaneous speech suggest that young children can monitor their speech, the mechanisms for detection and correction of speech errors in children are not well understood. In particular, there is little research on monitoring semantic errors in this population. This study provides a systematic investigation of detection and correction of semantic errors in children between the ages of 5 and 8 years as they produced sentences to describe simple visual events involving nine highly familiar animals (the moving animals task). Results showed that older children made fewer errors and corrected a larger proportion of the errors that they made than younger children. We then tested the prediction of a production-based account of error monitoring that the strength of the language production system, and specifically its semantic–lexical component, should be correlated with the ability to detect and repair semantic errors. Strength of semantic–lexical mapping, as well as lexical–phonological mapping, was estimated individually for children by fitting their error patterns, obtained from an independent picture-naming task, to a computational model of language production. Children’s picture-naming performance was predictive of their ability to monitor their semantic errors above and beyond age. This relationship was specific to the strength of the semantic–lexical part of the system, as predicted by the production-based monitor
Tunneling of massive and charged particles from noncommutative Reissner-Nordstr\"{o}m black hole
Massive charged and uncharged particles tunneling from commutative
Reissner-Nordstrom black hole horizon has been studied with details in
literature. Here, by adopting the coherent state picture of spacetime
noncommutativity, we study tunneling of massive and charged particles from a
noncommutative inspired Reissner-Nordstrom black hole horizon. We show that
Hawking radiation in this case is not purely thermal and there are correlations
between emitted modes. These correlations may provide a solution to the
information loss problem. We also study thermodynamics of noncommutative
horizon in this setup.Comment: 10 pages, 2 figure
On the dissipative non-minimal braneworld inflation
We study the effects of the non-minimal coupling on the dissipative dynamics
of the warm inflation in a braneworld setup, where the inflaton field is
non-minimally coupled to induced gravity on the warped DGP brane. We study with
details the effects of the non-minimal coupling and dissipation on the
inflationary dynamics on the normal DGP branch of this scenario in the
high-dissipation and high-energy regime. We show that incorporation of the
non-minimal coupling in this setup decreases the number of e-folds relative to
the minimal case. We also compare our model parameters with recent
observational data.Comment: 32 pages, 6 figures. arXiv admin note: substantial text overlap with
arXiv:1001.044
Minimal Length and the Quantum Bouncer: A Nonperturbative Study
We present the energy eigenvalues of a quantum bouncer in the framework of
the Generalized (Gravitational) Uncertainty Principle (GUP) via quantum
mechanical and semiclassical schemes. In this paper, we use two equivalent
nonperturbative representations of a deformed commutation relation in the form
[X,P]=i\hbar(1+\beta P^2) where \beta is the GUP parameter. The new
representation is formally self-adjoint and preserves the ordinary nature of
the position operator. We show that both representations result in the same
modified semiclassical energy spectrum and agrees well with the quantum
mechanical description.Comment: 14 pages, 2 figures, to appear in Int. J. Theor. Phy
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