scholarly journals Thermodynamics of Charged Rotating Dilaton Black Branes Coupled to Logarithmic Nonlinear Electrodynamics

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
A. Sheykhi ◽  
M. H. Dehghani ◽  
M. Kord Zangeneh
Keyword(s):  
Thermal Stability ◽  
Electromagnetic Coupling ◽  
Nonlinear Electrodynamics ◽  
Black Brane ◽  
Dilaton Field ◽  
Coupling Constant ◽  
De Sitter ◽  
New Class ◽  
Unstable Phase ◽  
Complete Set

We construct a new class of charged rotating black brane solutions in the presence of logarithmic nonlinear electrodynamics with complete set of the rotation parameters in arbitrary dimensions. The topology of the horizon of these rotating black branes is flat, while due to the presence of the dilaton field the asymptotic behavior of them is neither flat nor (anti-)de Sitter [(A)dS]. We investigate the physical properties of the solutions. The mass and angular momentum of the spacetime are obtained by using the counterterm method inspired by AdS/CFT correspondence. We derive temperature, electric potential, and entropy associated with the horizon and check the validity of the first law of thermodynamics on the black brane horizon. We study thermal stability of the solutions in both canonical and grand-canonical ensemble and disclose the effects of the rotation parameter, nonlinearity of electrodynamics, and dilaton field on the thermal stability conditions. We find the solutions are thermally stable forα<1, while forα>1the solutions may encounter an unstable phase, whereαis dilaton-electromagnetic coupling constant.

scholarly journals Thermodynamics of rotating black branes in higher dimensional Einstein – nonlinear electrodynamics – dilaton gravity

2016 ◽  
Vol 94 (1) ◽  
pp. 58-70 ◽  
Author(s):  
A. Sheykhi ◽  
S.H. Hendi
Keyword(s):  
Thermal Stability ◽  
Causal Structure ◽  
Space Time ◽  
Nonlinear Electrodynamics ◽  
Thermodynamic Quantities ◽  
Black Brane ◽  
Dilaton Field ◽  
Field Equations ◽  
Liouville Type ◽  
Counter Term

In this paper, we propose a n-dimensional action in which gravity is coupled to exponential nonlinear electrodynamics and scalar dilaton field with Liouville-type potential. By varying the action, we obtain the field equations. Then, we construct a new class of charged, rotating black brane solutions, with k = [(n – 1)/2] rotation parameters, of this theory. Because of the presence of the Liouville-type dilaton potential, the asymptotic behavior of the obtained solutions is neither flat nor (anti)-de Sitter. We investigate the causal structure of the space–time in ample details. We find the suitable counter term that removes the divergences of the action in the presence of the dilaton field, and calculate the conserved and thermodynamic quantities of the space–time. Interestingly enough, we find that the conserved quantities crucially depend on the dilaton coupling constant, α, while they are independent of the nonlinear parameter, β. We also check the validity of the first law of thermodynamics on the black brane horizon. Finally, we study thermal stability of the solutions by computing the heat capacity in the canonical ensemble. We disclose the effects of rotation parameter, nonlinearity of electrodynamics, and dilaton field on the thermal stability conditions.

scholarly journals Asymptotically anti-de Sitter magnetic branes in (n + 1)-dimensional dilaton gravity

2011 ◽  
Vol 89 (11) ◽  
pp. 1163-1169 ◽  
Author(s):  
M.H. Dehghani ◽  
A. Bazrafshan
Keyword(s):  
Longitudinal Magnetic Field ◽  
Conserved Quantities ◽  
Dilaton Field ◽  
Dilaton Gravity ◽  
Coupling Constant ◽  
De Sitter ◽  
Conformal Field ◽  
New Class ◽  
Deficit Angle ◽  
Rotation Parameters

We present a new class of asymptotically anti-de Sitter (AdS) magnetic solutions in (n + 1)-dimensional dilaton gravity in the presence of an appropriate combination of three Liouville-type potentials. This class of solutions is asymptotically AdS in six and higher dimensions and yields a space–time with a longitudinal magnetic field generated by a static brane. These solutions have no curvature singularity and no horizons but have a conic geometry with a deficit angle. We find that the brane tension depends on the dilaton field and approaches a constant as the coupling constant of the dilaton field goes to infinity. We generalized this class of solutions to the case of spinning magnetic solutions and find that, when one or more rotation parameters are nonzero, the brane has a net electric charge that is proportional to the magnitude of the rotation parameters. Finally, we used the counterterm method inspired by AdS – conformal field theory correspondence and computed the conserved quantities of these space–times. We found that the conserved quantities do not depend on the dilaton field, which is evident from the fact that the dilaton field vanishes on the boundary at infinity.

scholarly journals Rotating Dilaton Black Strings Coupled to Exponential Nonlinear Electrodynamics

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Ahmad Sheykhi
Keyword(s):  
Nonlinear Electrodynamics ◽  
Thermodynamic Quantities ◽  
Nonlinear Electrodynamic ◽  
Dilaton Field ◽  
Dilaton Gravity ◽  
Black String ◽  
Liouville Type ◽  
New Class ◽  
Type Potential ◽  
Exponential Nonlinear Electrodynamics

We construct a new class of charged rotating black string solutions coupled to dilaton and exponential nonlinear electrodynamic fields with cylindrical or toroidal horizons in the presence of a Liouville-type potential for the dilaton field. Due to the presence of the dilaton field, the asymptotic behaviors of these solutions are neither flat nor (A)dS. We analyze the physical properties of the solutions in detail. We compute the conserved and thermodynamic quantities of the solutions and verify the first law of thermodynamics on the black string horizon. When the nonlinear parameterβ2goes to infinity, our results reduce to those of black string solutions in Einstein-Maxwell-dilaton gravity.

Thermodynamics of charged A(dS) black holes with quadratically-extended electrodynamics

2020 ◽  
Vol 17 (02) ◽  
pp. 2050020 ◽  
Author(s):  
M. Dehghani
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Electric Potential ◽  
Mass Formula ◽  
Black Hole Entropy ◽  
De Sitter ◽  
Two Phase ◽  
New Class ◽  
Hole Charge ◽  
Complete Set

In this paper, the Einstein-nonlinear electromagnetic theory has been studied in the four-dimensional de Sitter (dS) and anti-de Sitter (AdS) spacetimes. A new class of nonlinearly charged A(dS) black hole solution, in the presence of quadratically-extended Maxwell field, has been obtained and the thermodynamical properties have been analyzed. The black hole entropy, temperature and electric potential have been calculated, making use of the geometric methods. Through a Smarr mass formula the black hole mass has been written as a function of the complete set of extensive parameters (i.e. charge and entropy). It has been found that the intensive parameters (i.e. electric potential and temperature) obtained from the mass formula coincide with their values obtained from geometric approaches. It confirms the validity of the first law of black hole thermodynamics. A black hole stability analysis has been performed from the canonical ensemble approach, regarding the black hole heat capacity with the black hole charge as a constant. The points of type one and type two phase transitions, and the ranges at which the new charged A(dS) black holes are locally stable have been determined. Also, for the new charged black holes to be physically reasonable, their charge has been restricted to some specific ranges.

scholarly journals Geometries with mismatched branes

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Andreas Karch ◽  
Lisa Randall
Keyword(s):  
Boundary Conditions ◽  
Effective Action ◽  
Cosmological Models ◽  
Time Dependent ◽  
De Sitter ◽  
Stabilization Mechanism ◽  
New Class ◽  
Vacuum Solutions ◽  
Single Coordinate

Abstract We study Randall-Sundrum two brane setups with mismatched brane tensions. For the vacuum solutions, boundary conditions demand that the induced metric on each of the branes is either de Sitter, Anti-de Sitter, or Minkowski. For incompatible boundary conditions, the bulk metric is necessarily time-dependent. This introduces a new class of time-dependent solutions with the potential to address cosmological issues and provide alternatives to conventional inflationary (or contracting) scenarios. We take a first step in this paper toward such solutions. One important finding is that the resulting solutions can be very succinctly described in terms of an effective action involving only the induced metric on either one of the branes and the radion field. But the full geometry cannot necessarily be simply described with a single coordinate patch. We concentrate here on the time- dependent solutions but argue that supplemented with a brane stabilization mechanism one can potentially construct interesting cosmological models this way. This is true both with and without a brane stabilization mechanism.

scholarly journals A radical departure from the ‘steady-state’ concept in cosmology

1966 ◽  
Vol 290 (1421) ◽  
pp. 162-176 ◽  
Keyword(s):  
Steady State ◽  
Cosmic Rays ◽  
High Energy ◽  
Expansion Rate ◽  
Coupling Constant ◽  
De Sitter ◽  
Observable Universe ◽  
State Expansion ◽  
The Masses ◽  
Creation Of Matter

The results in this paper are based on an entirely different choice of the undetermined coupling constant f which appears in the theory of creation of matter. Previously f was chosen to make the steady-state expansion rate coincident with the observed expansion rate. Now that we take a much larger value for f , the corresponding steady-state expansion rate is much greater than the observed value. We interpret this difference as showing that we live in a wide, possibly temporary, fluctuation from the steady-state situation. The expansion rate in such a fluctuation follows the Einstein-de Sitter relations. The natural scale set by the new steady-state corresponds to the masses of clusters of galaxies, we obtain 10 13 M0 instead of 10 23 M@ for the ‘observable universe’. It is suggested that elliptical galaxies were formed early in the development of a fluctuation. Our discussion of high energy phenomena leads to im m ediate explanations of the energy spectrum of cosmic rays, of the presence of e + in cosmic rays and of the rate of energy production associated with radio sources.

scholarly journals On the running electromagnetic coupling constant at $M_Z$

1999 ◽  
Vol 9 (4) ◽  
pp. 551-556 ◽  
Author(s):  
J.G. Körner ◽  
A.A. Pivovarov ◽  
K. Schilcher
Keyword(s):  
Electromagnetic Coupling ◽  
Coupling Constant

scholarly journals A Millennial Myosin Census

2001 ◽  
Vol 12 (4) ◽  
pp. 780-794 ◽  
Author(s):  
Jonathan S. Berg ◽  
Bradford C. Powell ◽  
Richard E. Cheney
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Phylogenetic Analysis ◽  
Molecular Basis ◽  
General Interest ◽  
Class Iii ◽  
New Class ◽  
The Past ◽  
Human Genes ◽  
Complete Set ◽  
Myosin Superfamily

The past decade has seen a remarkable explosion in our knowledge of the size and diversity of the myosin superfamily. Since these actin-based motors are candidates to provide the molecular basis for many cellular movements, it is essential that motility researchers be aware of the complete set of myosins in a given organism. The availability of cDNA and/or draft genomic sequences from humans,Drosophila melanogaster, Caenorhabditis elegans, Arabidopsis thaliana,Saccharomyces cerevisiae, Schizosaccharomyces pombe, andDictyostelium discoideum has allowed us to tentatively define and compare the sets of myosin genes in these organisms. This analysis has also led to the identification of several putative myosin genes that may be of general interest. In humans, for example, we find a total of 40 known or predicted myosin genes including two new myosins-I, three new class II (conventional) myosins, a second member of the class III/ninaC myosins, a gene similar to the class XV deafness myosin, and a novel myosin sharing at most 33% identity with other members of the superfamily. These myosins are in addition to the recently discovered class XVI myosin with N-terminal ankyrin repeats and two human genes with similarity to the class XVIII PDZ-myosin from mouse. We briefly describe these newly recognized myosins and extend our previous phylogenetic analysis of the myosin superfamily to include a comparison of the complete or nearly complete inventories of myosin genes from several experimentally important organisms.

scholarly journals Minimal surfaces and generalized Einstein–Maxwell-dilaton theory

2019 ◽  
Vol 34 (12) ◽  
pp. 1950061
Author(s):  
M. Butler ◽  
A. M. Ghezelbash
Keyword(s):  
Cosmological Constant ◽  
Physical Properties ◽  
Minimal Surfaces ◽  
Higher Dimensions ◽  
Coupling Constants ◽  
Dilaton Field ◽  
Coupling Constant ◽  
Maxwell Theory ◽  
Five Dimensions ◽  
Cosmological Solutions

We present novel classes of nonstationary solutions to the five-dimensional generalized Einstein–Maxwell-dilaton theory with cosmological constant, in which the Maxwell’s field and the cosmological constant couple to the dilaton field. In the first class of solutions, the two nonzero coupling constants are different, while in the second class of solutions, the two coupling constants are equal to each other. We find consistent cosmological solutions with positive, negative or zero cosmological constant, where the cosmological constant depends on the value of one coupling constant in the theory. Moreover, we discuss the physical properties of the five-dimensional solutions and the uniqueness of the solutions in five dimensions by showing the solutions with different coupling constants cannot be uplifted to any Einstein–Maxwell theory in higher dimensions.

NUMERICAL ANALYSIS OF GUTs PREDICTIONS IN THE LIGHT OF RECENT RESULTS FROM LEP

1992 ◽  
Vol 07 (35) ◽  
pp. 3319-3330
Author(s):  
DARIUSZ GRECH
Keyword(s):  
Z Boson ◽  
Electromagnetic Coupling ◽  
Boson Mass ◽  
Threshold Effects ◽  
Coupling Constant ◽  
Central Values ◽  
Unified Theories ◽  
Proton Lifetime ◽  
Experimental Values ◽  
Best Fit

We find numerical best fit for sin 2 Θw(MZ), unifying mass MX and the proton lifetime τp as the outcome of analysis where experimental values of Z boson mass MZ, strong coupling constant αs(MZ) and electromagnetic coupling α0(MZ) are taken as the only input parameters. It is found that simple nonsupersymmetric models are unlikely to be realistic ones. On the other hand, we find the best numerical fit: sin 2Θw(MZ = 0.2330 ± 0.0007 (theor.) ± 0.0027 (exp.) , [Formula: see text] yr for supersymmetric unified theories with three generations. The central values require, however, that the supersymmetric mass Λs≲300 GeV . Possibilities of increasing this limit as well as cases with four generations and threshold effects are also discussed. Compact formulas for theoretical and experimental uncertainties involved in the analysis are also produced.

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