Implications for the hierarchy problem, inflation and geodesic motion from fiber fabric of spacetime

AbstractIn this paper, we represent a resolution for the hierarchy problem where the inverse size of the extra dimension and the fundamental Planck scale would all be of the order of the TeV scale by proposing a fiber fabric of spacetime. The origin of the large hierarchy is essentially due to the $$\cosh $$ cosh function which is physically originated from the dynamics of the horizontal metric in the vacuum of non-zero energy. In addition, the fiber fabric of spacetime allows us to resolve elegantly and naturally the problems of the chirality fermions and stabilizing potential for the size of the extra dimension, which are usually encountered in the higher dimensional theories. Then, we explore the inflation with the modulus of the extra dimension identified as the inflaton where our slow-roll inflationary model belongs to the E-model class with $$n=1$$ n = 1 . We calculate the main inflationary observables which are consistent with the present experiments. Finally, we study how the geodesic motion of neutral test particles gets modified from the extension of spacetime. We compute the radius of the photon sphere, the innermost stable circular orbit, the perihelion shift, the light bending angle, and the observables of the strong gravitational lensing and the retrolensing phenomenon. By comparing the predicted values with the experimental observations, we determine the constraints on the fiber fabric of spacetime.

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Large star/rose extra dimension with small leaves/petals

International Journal of Modern Physics A ◽

10.1142/s0217751x20501821 ◽

2020 ◽

Vol 35 (30) ◽

pp. 2050182

Author(s):

Florian Nortier

Keyword(s):

Extra Dimension ◽

Planck Scale ◽

Hierarchy Problem ◽

Large Extra Dimension ◽

Strongly Coupled ◽

Weak Scale ◽

Hidden Sector ◽

Petal Length ◽

Gauge Hierarchy ◽

The Right

In this paper, we propose to compactify a single Large Extra Dimension (LED) on a star/rose graph with a large number of identical leaves/petals. The 5D Planck scale can be chosen to be [Formula: see text] TeV which can provide a path to solve the gauge hierarchy problem. The leaf/petal length scale is of [Formula: see text], where [Formula: see text] GeV is the weak scale, without the large geometrical hierarchy of the traditional LED models to stabilize. The 4D fields of the SM are localized on a 3-brane at the central vertex of the star/rose graph. We predict a tower of feebly coupled weak scale Kaluza–Klein (KK) gravitons below a regime of strongly coupled gravitational phenomena above the TeV scale. Moreover, we reformulate in our setup the LED mechanism to generate light Dirac neutrinos, where the right-handed neutrinos are KK-modes of gauge singlet fermions propagating in the bulk. A large number of KK-gravitons and KK-neutrinos interact only gravitationally and thus constitute a hidden sector.

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Traversable wormholes in Einsteinian cubic gravity

Modern Physics Letters A ◽

10.1142/s0217732320500170 ◽

2019 ◽

Vol 35 (06) ◽

pp. 2050017 ◽

Cited By ~ 7

Author(s):

Mohammad Reza Mehdizadeh ◽

Amir Hadi Ziaie

Keyword(s):

Equation Of State ◽

Gravitational Lensing ◽

Energy Condition ◽

Higher Order ◽

Energy Conditions ◽

Geodesic Motion ◽

De Sitter ◽

Asymptotically Flat ◽

Traversable Wormholes ◽

Standard Energy

In this work, we investigate wormhole configurations described by a constant redshift function in Einstein-Cubic gravity ( ECG ). We derive analytical wormhole geometries by assuming a particular equation of state ( EoS ) and investigate the possibility that these solutions satisfy the standard energy conditions. We introduce exact asymptotically flat and anti-de Sitter (AdS) spacetimes that admit traversable wormholes. These solutions are obtained by imposing suitable values for the parameters of the theory so that the resulted geometries satisfy the weak energy condition ( WEC ) in the vicinity of the throat, due to the presence of higher-order curvature terms. Moreover, we find that AdS solutions satisfy the WEC throughout the spacetime. A description of the geodesic motion of time-like and null particles is presented for the obtained wormhole solutions. Also, using gravitational lensing effects, observational features of the wormhole structure are discussed.

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A NON-GEODESIC MOTION IN THE R-1 THEORY OF GRAVITY TUNED WITH OBSERVATIONS

Modern Physics Letters A ◽

10.1142/s0217732308026248 ◽

2008 ◽

Vol 23 (02) ◽

pp. 109-114 ◽

Cited By ~ 12

Author(s):

CHRISTIAN CORDA

Keyword(s):

Dark Matter ◽

High Order ◽

Ricci Scalar ◽

Geodesic Motion ◽

General Picture ◽

Test Particles ◽

Pioneer Anomaly ◽

Theories Of Gravity ◽

Theory Of Gravity

In the general picture of high order theories of gravity, recently, the R-1 theory has been analyzed in two different frameworks. In this letter a third context is added, considering an explicit coupling between the R-1 function of the Ricci scalar and the matter Lagrangian. The result is a non-geodesic motion of test particles which, in principle, could be connected with Dark Matter and Pioneer anomaly problems.

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Lyapunov exponent, ISCO and Kolmogorov–Senai entropy for Kerr–Kiselev black hole

The European Physical Journal C ◽

10.1140/epjc/s10052-021-08888-1 ◽

2021 ◽

Vol 81 (1) ◽

Author(s):

Monimala Mondal ◽

Farook Rahaman ◽

Ksh. Newton Singh

Keyword(s):

Black Holes ◽

Black Hole ◽

Lyapunov Exponent ◽

Circular Orbit ◽

Real Root ◽

Angular Frequency ◽

Geodesic Motion ◽

Radial Equation ◽

Stable Circular Orbit ◽

Innermost Stable Circular Orbit

AbstractGeodesic motion has significant characteristics of space-time. We calculate the principle Lyapunov exponent (LE), which is the inverse of the instability timescale associated with this geodesics and Kolmogorov–Senai (KS) entropy for our rotating Kerr–Kiselev (KK) black hole. We have investigate the existence of stable/unstable equatorial circular orbits via LE and KS entropy for time-like and null circular geodesics. We have shown that both LE and KS entropy can be written in terms of the radial equation of innermost stable circular orbit (ISCO) for time-like circular orbit. Also, we computed the equation marginally bound circular orbit, which gives the radius (smallest real root) of marginally bound circular orbit (MBCO). We found that the null circular geodesics has larger angular frequency than time-like circular geodesics ($$Q_o > Q_{\sigma }$$ Q o > Q σ ). Thus, null-circular geodesics provides the fastest way to circulate KK black holes. Further, it is also to be noted that null circular geodesics has shortest orbital period $$(T_{photon}< T_{ISCO})$$ ( T photon < T ISCO ) among the all possible circular geodesics. Even null circular geodesics traverses fastest than any stable time-like circular geodesics other than the ISCO.

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Particle motion around generic black holes coupled to non-linear electrodynamics

The European Physical Journal C ◽

10.1140/epjc/s10052-019-7286-2 ◽

2019 ◽

Vol 79 (9) ◽

Cited By ~ 5

Author(s):

Jaroslav Vrba ◽

Ahmadjon Abdujabbarov ◽

Arman Tursunov ◽

Bobomurat Ahmedov ◽

Zdeněk Stuchlík

Keyword(s):

Black Hole ◽

Energy Conditions ◽

Test Particles ◽

Stable Circular Orbit ◽

Spin Parameter ◽

Non Linear ◽

Innermost Stable Circular Orbit ◽

Charge Parameter ◽

Upper Estimate ◽

Black Hole Solutions

Abstract We study spherically symmetric magnetically charged generic black hole solutions of general relativity coupled to non-linear electrodynamics (NED). For characteristic values of the generic spacetime parameters we give the position of horizons in dependence on the charge parameter, demonstrating separation of the black hole and no-horizon solutions, and possibility of existence of solutions containing three horizons. We show that null, weak and strong energy conditions are violated when the outer horizon is approaching the center. We study effective potentials for photons and massive test particles and location of circular photon orbits (CPO) and innermost stable circular orbit (ISCO). We show that the unstable photon orbit can become stable, leading to the possibility of photon capture which affects on silhouette of the central object. The position of ISCO approaches the horizon with increasing charge parameter q and the energy at ISCO decreases with increasing charge parameter. We investigate this phenomenon and summarize for a variety of the generic spacetime parameters the upper estimate on the spin parameter of the Kerr black which can be mimicked by the generic charged black hole solutions.

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Orbital dynamics of the gravitational field of stringy black holes

Modern Physics Letters A ◽

10.1142/s0217732314501442 ◽

2014 ◽

Vol 29 (29) ◽

pp. 1450144 ◽

Cited By ~ 3

Author(s):

Yu Zhang ◽

Jin-Ling Geng ◽

En-Kun Li

Keyword(s):

Black Holes ◽

Angular Momentum ◽

Gravitational Field ◽

Phase Plane ◽

Equations Of Motion ◽

Orbital Dynamics ◽

Phase Plane Analysis ◽

Test Particles ◽

Stable Circular Orbit ◽

The Stability

In this paper, we study the orbital dynamics of the gravitational field of stringy black holes by analyzing the effective potential and the phase plane diagram. By solving the equation of Lagrangian, the general relativistic equations of motion in the gravitational field of stringy black holes are given. It is easy to find that the motion of test particles depends on the energy and angular momentum of the test particles. Using the phase plane analysis method and combining the conditions of the stability, we discuss different types of the test particles' orbits in the gravitational field of stringy black holes. We get the innermost stable circular orbit which occurs at r min = 5.47422 and when the angular momentum b ≤ 4.3887 the test particles will fall into the black hole.

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Null and Timelike Geodesics near the Throats of Phantom Scalar Field Wormholes

Universe ◽

10.3390/universe6100183 ◽

2020 ◽

Vol 6 (10) ◽

pp. 183

Author(s):

Ivan Potashov ◽

Julia Tchemarina ◽

Alexander Tsirulev

Keyword(s):

Black Holes ◽

Scalar Field ◽

Circular Orbit ◽

Realistic Model ◽

Test Particles ◽

Stable Circular Orbit ◽

Phantom Scalar ◽

Metric Function ◽

Bound Orbits ◽

Phantom Scalar Field

We study geodesic motion near the throats of asymptotically flat, static, spherically symmetric traversable wormholes supported by a self-gravitating minimally coupled phantom scalar field with an arbitrary self-interaction potential. We assume that any such wormhole possesses the reflection symmetry with respect to the throat, and consider only its observable “right half”. It turns out that the main features of bound orbits and photon trajectories close to the throats of such wormholes are very different from those near the horizons of black holes. We distinguish between wormholes of two types, the first and second ones, depending on whether the redshift metric function has a minimum or maximum at the throat. First, it turns out that orbits located near the centre of a wormhole of any type exhibit retrograde precession, that is, the angle of pericentre precession is negative. Second, in the case of high accretion activity, wormholes of the first type have the innermost stable circular orbit at the throat while those of the second type have the resting-state stable circular orbit in which test particles are at rest at all times. In our study, we have in mind the possibility that the strongly gravitating objects in the centres of galaxies are wormholes, which can be regarded as an alternative to black holes, and the scalar field can be regarded as a realistic model of dark matter surrounding galactic centres. In this connection, we discuss qualitatively some observational aspects of results obtained in this article.

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Softly broken conformal symmetry and the stability of the electroweak scale

Modern Physics Letters A ◽

10.1142/s0217732315500066 ◽

2015 ◽

Vol 30 (02) ◽

pp. 1550006 ◽

Cited By ~ 19

Author(s):

Piotr H. Chankowski ◽

Adrian Lewandowski ◽

Krzysztof A. Meissner ◽

Hermann Nicolai

Keyword(s):

Field Theory ◽

Standard Model ◽

Conformal Symmetry ◽

Planck Scale ◽

Effective Field ◽

Effective Theory ◽

Minimal Extension ◽

Fundamental Theory ◽

Hierarchy Problem ◽

Physical Scale

We point out a possible mechanism by which the electroweak hierarchy problem can be avoided in the low energy effective quantum field theory. Assuming the existence of a UV complete underlying fundamental theory and treating the cutoff scale Λ of the effective field theory as a real physical scale we argue that the hierarchy problem would be solved if the coefficient in front of quadratic divergences vanished at the scale Λ, and if the effective theory mass parameters fixed at Λ by the fundamental theory were hierarchically smaller than Λ itself. While this mechanism most probably cannot work in the Standard Model if the scale Λ is to be close to the Planck scale, we show that it can work in a minimal extension (Conformal Standard Model) proposed recently for a different implementation of conformal symmetry breaking.

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