scholarly journals Geodesic Circular Orbits Sharing the Same Orbital Frequencies in the Black String Spacetime

Galaxies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 40
Author(s):  
Sanjar Shaymatov ◽  
Farruh Atamurotov
Keyword(s):  
Parameter Space ◽  
Extra Dimension ◽  
Spatial Dimension ◽  
Critical Value ◽  
Conserved Quantity ◽  
Black String ◽  
Circular Orbits ◽  
Spacetime Geometry ◽  
Extra Spatial Dimension

We consider isofrequency pairing of geodesic orbits that share the same three orbital frequencies associated with Ωr^, Ωφ^, and Ωω^ in a particular region of parameter space around black string spacetime geometry. We study the effect of a compact extra spatial dimension on the isofrequency pairing of geodesic orbits and show that such orbits would occur in the allowed region when particles move along the black string. We find that the presence of the compact extra dimension leads to an increase in the number of the isofrequency pairing of geodesic orbits. Interestingly we also find that isofrequency pairing of geodesic orbits in the region of parameter space cannot be realized beyond the critical value Jcr≈0.096 of the conserved quantity of the motion arising from the compact extra spatial dimension.

PHYSICAL ASPECTS OF SOLITONS IN (4+1) GRAVITY

1995 ◽  
Vol 04 (05) ◽  
pp. 639-659 ◽  
Author(s):  
ANDREW BILLYARD ◽  
PAUL S. WESSON ◽  
DIMITRI KALLIGAS
Keyword(s):  
Physical Properties ◽  
Extra Dimension ◽  
Dimensional Case ◽  
Schwarzschild Solution ◽  
Circular Orbits ◽  
Know How ◽  
Fifth Dimension ◽  
Klein Theory ◽  
Limiting Case ◽  
Kaluza Klein

The augmentation of general relativity’s spacetime by one or more dimensions is described by Kaluza-Klein theory and is within testable limits. Should an extra dimension be observable and significant, it would be beneficial to know how physical properties would differ from “conventional” relativity. In examining the class of five-dimensional solutions analogous to the four-dimensional Schwarzschild solution, we examine where the origin to the system is located and note that it can differ from the four-dimensional case. Furthermore, we study circular orbits and find that the 5D case is much richer; photons can have stable circular orbits in some instances, and stable orbits can exist right to the new origin in others. Finally, we derive both gravitational and inertial masses and find that they do not generally agree, although they can in a limiting case. For all three examinations, it is possible to obtain the four-dimensional results in one limiting case, that of the Schwarzschild solution plus a flat fifth dimension, and that the differences between 4D and 5D occur when the fifth dimension obtains any sort of significance.

scholarly journals PROPERTIES OF ACCRETION SHOCKS IN VISCOUS FLOWS WITH COOLING EFFECTS

2004 ◽  
Vol 13 (09) ◽  
pp. 1955-1972 ◽  
Author(s):  
SANTABRATA DAS ◽  
SANDIP K. CHAKRABARTI
Keyword(s):  
Shock Wave ◽  
Angular Momentum ◽  
Shock Waves ◽  
Thermodynamic Parameters ◽  
Parameter Space ◽  
Viscous Flows ◽  
Critical Value ◽  
The Other ◽  
Accretion Flows ◽  
Cooling Effects

Low angular momentum accretion flows can have standing and oscillating shock waves. We study the region of the parameter space in which multiple sonic points occur in viscous flows in presence of various cooling effects such as bremsstrahlung and Comptonization. We also quantify the parameter space in which shocks are steady or oscillating. We find that cooling induces effects opposite to heating by viscosity even in modifying the topology of the solutions, though one can never be exactly balanced by the other due to their dissimilar dependence on dynamic and thermodynamic parameters. We show that beyond a critical value of cooling, the flow ceases to contain a shock wave.

scholarly journals Inflation with a class of concave inflaton potentials in Randall–Sundrum model

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Ngo Phuc Duc Loc
Keyword(s):  
Planck Scale ◽  
Spatial Dimension ◽  
Small Field ◽  
Braneworld Cosmology ◽  
Extra Spatial Dimension ◽  
Good Agreement

Abstract We investigate inflation with a class of concave inflaton potentials of the form $$\sim \phi ^n$$∼ϕn$$(0<n<1)$$(0<n<1) in the Randall–Sundrum model with an infinite extra spatial dimension. We show that this class of models is much more in good agreement with observations compared to the standard inflation. We also find the range of the five-dimensional Planck scale ($$M_5$$M5) and show that large tensor-to-scalar ratios do not eliminate small-field inflation in braneworld cosmology.

scholarly journals Eccentric grazing envelope evolution towards Type IIb supernova progenitors

2020 ◽  
Vol 497 (1) ◽  
pp. 855-864
Author(s):  
Dmitry Shishkin ◽  
Noam Soker
Keyword(s):  
Parameter Space ◽  
Binary Systems ◽  
Circular Orbits ◽  
High Eccentricity ◽  
Mass Removal ◽  
Common Envelope ◽  
Hydrogen Mass ◽  
Very High ◽  
Initial Orbit

ABSTRACT We simulate the evolution of eccentric binary systems in the frame of the grazing envelope evolution (GEE) channel for the formation of Type IIb supernovae (SNe IIb), and find that extra mass removal by jets increases the parameter space for the formation of SNe IIb in this channel. To explore the role of eccentricity and the extra mass removal by jets, we use the stellar evolutionary code mesa binary. The initial primary and secondary masses are M1, i = 15 and M2, i = 2.5 M⊙. We examine initial semimajor axes of 600–1000 R⊙, and eccentricities of e = 0–0.9. Both Roche lobe overflow (RLOF) and mass removal by jets, followed by a wind, leave a hydrogen mass in the exploding star of MH, f ≈ 0.05 M⊙, compatible with an SN IIb progenitor. When the initial orbit is not circular, the final orbit might have a very high eccentricity. In many cases, with and without the extra mass removal by jets, the system can enter a common envelope evolution (CEE) phase, and then gets out from it. For some ranges of eccentricities, the jets are more efficient in preventing the CEE. Despite the large uncertainties, extra mass removal by jets substantially increases the likelihood of the system to get out from a CEE. This strengthens earlier conclusions for circular orbits. In some cases, RLOF alone, without mass removal by jets, can form SN IIb progenitors. We estimate that the extra mass removal by jets in the GEE channel increases the number of progenitors relative to that by RLOF alone by about a factor of 2.

scholarly journals EXACT SOLUTIONS OF EMBEDDING THE 4D UNIVERSE IN A 5D EINSTEIN MANIFOLD

2008 ◽  
Vol 17 (02) ◽  
pp. 257-263 ◽  
Author(s):  
XIN-HE MENG ◽  
JIE REN ◽  
HONG-GUANG ZHANG
Keyword(s):  
Cosmological Constant ◽  
Exact Solutions ◽  
Einstein Equation ◽  
Power Law ◽  
Einstein Manifold ◽  
Spatial Dimension ◽  
Λcdm Model ◽  
Extra Spatial Dimension ◽  
The Right ◽  
Real Universe

One of the simplest ways to extend 4D cosmological models is to add another spatial dimension to make them 5D. In particular, it has been shown that the simplest of such 5D models, i.e. one in which the right-hand side of the Einstein equation is empty, induces a 4D nonempty universe. Accordingly, the origin of matter in a real 4D universe might be mathematically attributed to the existence of one (fictitious) extra spatial dimension. Here we consider the case of an empty 5D universe possessing a cosmological constant Λ and obtain exact solutions for both positive and negative values of the Λ. It is seen that such a model can naturally reduce to a power law ΛCDM model for the real universe. Further, it can be seen that the arbitrary constants and functions appearing in this model are endowed with definite physical meanings.

scholarly journals A PRECISION TEST FOR AN EXTRA SPATIAL DIMENSION USING BLACK-HOLE-PULSAR BINARIES

2011 ◽  
Vol 737 (2) ◽  
pp. L28 ◽  
Author(s):  
John H. Simonetti ◽  
Michael Kavic ◽  
Djordje Minic ◽  
Umair Surani ◽  
Vipin Vijayan
Keyword(s):  
Black Hole ◽  
Spatial Dimension ◽  
Extra Spatial Dimension ◽  
Precision Test

scholarly journals PROTON DECAY, FERMION MASSES AND TEXTURE FROM EXTRA DIMENSIONS IN SUSY GUT's

2004 ◽  
Vol 19 (11) ◽  
pp. 1715-1736 ◽  
Author(s):  
MITSURU KAKIZAKI ◽  
MASAHIRO YAMAGUCHI
Keyword(s):  
Extra Dimension ◽  
Mass Matrix ◽  
Spatial Dimension ◽  
Proton Decay ◽  
Mass Scale ◽  
Wave Functions ◽  
Fermion Mass ◽  
Quark Masses ◽  
Fermion Masses ◽  
The Hierarchical Structure

In supersymmetry, there are gauge invariant dimension 5 proton decay operators which must be suppressed by a mass scale much larger than the Planck mass. It is natural to expect that this suppression should be explained by a mechanism that explains the hierarchical structure of the fermion mass matrices. We apply this argument to the case where wave functions of chiral multiplets are localized under a kink background along an extra spatial dimension and the Yukawa couplings as well as the coefficients of the proton decay operators are determined by the overlap of the relevant wave functions. A configuration is found in the context of SU(5) supersymmetric grand unified theory that yields realistic values of quark masses, mixing angles, CP phase and charged lepton masses and sufficiently small genuine dimension 5 proton decay operators. Inclusion of SU(5) breaking effects is essential in order to obtain non-vanishing CP phase as well as correct lepton masses. The resulting mass matrix has a texture structure in which texture zeros are a consequence of extremely small overlap of the wave functions. Our approach requires explicit breaking of supersymmetry in the extra dimension, which can be realized in (de)constructing extra dimension.

scholarly journals On a nonlinear hydromagnetic convection under a rotational constraint

1980 ◽  
Vol 22 (2) ◽  
pp. 161-174 ◽  
Author(s):  
N. Riahi
Keyword(s):  
Parameter Space ◽  
Mean Field ◽  
Vertical Axis ◽  
Field Approximation ◽  
Critical Value ◽  
Horizontal Layer ◽  
Heat Fluxes ◽  
Wave Number ◽  
Mean Field Approximation ◽  
Horizontal Wave

AbstractNonlinear hydromagnetic convection in a horizontal layer of fluid rotating about the vertical axis is investigated using the mean field approximation. The boundary layer method is used assuming large Rayleigh number R for different ranges of the Chandrasekhar number Q and the Taylor number Ta. The heat flux F is determined for the value of the horizontal wave number α which maximizes F. It is shown that, for certain regions of the parameter space (R, Q, Ta), F and α change discontinuously for Ta greater than some critical value (given R and Q). Thus, for Ta about this critical value, wave numbers and heat fluxes of two different values will be predicted simultaneously. Also, for certian regions of the parameter space, the field can facilitate convection, but rotation can facilitate convection only for sufficiently large Ta.

scholarly journals ACCELERATING UNIVERSE FROM EXTRA SPATIAL DIMENSION

2006 ◽  
Vol 21 (19n20) ◽  
pp. 4035-4044 ◽  
Author(s):  
S. CHATTERJEE ◽  
A. BANERJEE ◽  
Y. Z. ZHANG
Keyword(s):  
Negative Pressure ◽  
Extra Dimensions ◽  
Spatial Dimension ◽  
Big Bang ◽  
Accelerating Universe ◽  
Higher Dimensional ◽  
Matter Theory ◽  
Desirable Feature ◽  
Extra Spatial Dimension ◽  
Induced Matter

We present a simple higher dimensional FRW-type of model where the acceleration is apparently caused by the presence of the extra dimensions. Assuming an ansatz in the form of the deceleration parameter, we get a class of solutions some of which shows the desirable feature of dimensional reduction as well as reasonably good physical properties of matter. Interestingly we do not have to invoke an extraneous scalar field or a cosmological constant to account for this acceleration. One argues that the terms containing the higher dimensional metric coefficients produces an extra negative pressure that apparently drives the inflation of the 4D space with an accelerating phase. It is further found that in line with the physical requirements our model admits of a decelerating phase in the early era along with an accelerating phase at present. Further the models asymptotically mimic a steady-state-type of universe although it starts from a big-bang-type of singularity. Correspondence to Wesson's induced matter theory is also briefly discussed and, in line with it, it is argued that the terms containing the higher dimensional metric coefficients apparently creates a negative pressure which drives the inflation of the 3-space with an accelerating phase.

scholarly journals KK graviton resonance and cascade decays in warped gravity

2017 ◽  
Vol 32 (33) ◽  
pp. 1745006 ◽  
Author(s):  
Barry M. Dillon ◽  
Chengcheng Han ◽  
Hyun Min Lee ◽  
Myeonghun Park
Keyword(s):  
Wave Function ◽  
Dark Matter ◽  
Higgs Boson ◽  
Parameter Space ◽  
Extra Dimension ◽  
Scale Invariance ◽  
Direct Photon ◽  
Angular Distributions ◽  
Composite Higgs ◽  
Kaluza Klein

We consider the Kaluza–Klein (KK) graviton and its decays in the presence of the light radion, the modulus of extra dimension, appearing naturally light due to classical scale invariance in warped gravity. Due to the presence of a sizable wave function overlap in the extra dimension between the KK graviton and the radion, the KK graviton can decay largely into a pair of radions, each of which decays into a pair of collimated photons or photon-jets. Focusing on the setup where the KK graviton has suppressed couplings to the Higgs boson and fermions, we discuss the bounds on the light radion in the parameter space where the photon-jets are relevant. Moreover, we pursue the possibility of distinguishing the scenario from the case with direct photon contributions by the angular distributions of photons in the LHC Run 2. Roles of KK graviton and radion as mediators of dark matter interactions, extensions with brane kinetic terms and the model with a holographic composite Higgs are also addressed.

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