scholarly journals Unitarity in KK-graviton production, a case study in warped extra-dimensions

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
A. de Giorgi ◽  
S. Vogl
Keyword(s):  
Extra Dimensions ◽  
Sum Rules ◽  
Effective Theory ◽  
Higher Dimensional ◽  
Massive Spin ◽  
The Matrix ◽  
Dimensional Gravity ◽  
Warped Extra Dimensions ◽  
Kaluza Klein

Abstract The Kaluza-Klein (KK) decomposition of higher-dimensional gravity gives rise to a tower of KK-gravitons in the effective four-dimensional (4D) theory. Such massive spin-2 fields are known to be connected with unitarity issues and easily lead to a breakdown of the effective theory well below the naive scale of the interaction. However, the breakdown of the effective 4D theory is expected to be controlled by the parameters of the 5D theory. Working in a simplified Randall-Sundrum model we study the matrix elements for matter annihilations into massive gravitons. We find that truncating the KK-tower leads to an early breakdown of perturbative unitarity. However, by considering the full tower we obtain a set of sum rules for the couplings between the different KK-fields that restore unitarity up to the scale of the 5D theory. We prove analytically that these are fulfilled in the model under consideration and present numerical tests of their convergence. This work complements earlier studies that focused on graviton self-interactions and yields additional sum rules that are required if matter fields are incorporated into warped extra-dimensions.

scholarly journals LABORATORY LIMITS ON THEORIES WITH STERILE NEUTRINOS IN THE BULK

2001 ◽  
Vol 16 (supp01c) ◽  
pp. 931-933 ◽  
Author(s):  
ARA IOANNISIAN ◽  
APOSTOLOS PILAFTSIS
Keyword(s):  
Extra Dimensions ◽  
Large Extra Dimensions ◽  
Effective Theory ◽  
Sterile Neutrinos ◽  
Order Unity ◽  
Yukawa Couplings ◽  
Original Order ◽  
Higher Dimensional ◽  
Decoupling Effect ◽  
Kaluza Klein

We discuss the phenomenological consequences of theories which describe sterile neutrinos in large extra dimensions, in the so-called bulk. We briefly outline how the cumulative non-decoupling effect due to the tower of Kaluza-Klein singlet neutrinos may equivalently be described by a higher-dimensional effective theory with original order-unity Yukawa couplings. Based on this cumulative phenomenon, we obtain strong constraints on the fundamental quantum gravity scale and/or on the higher-dimensional Yukawa couplings.

scholarly journals Dark matter interacting via a massive spin-2 mediator in warped extra-dimensions

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
A. de Giorgi ◽  
S. Vogl
Keyword(s):  
Dark Matter ◽  
Extra Dimensions ◽  
Center Of Mass ◽  
High Energy ◽  
Effective Theory ◽  
Full Field ◽  
Longitudinal Modes ◽  
Energy Behavior ◽  
Massive Spin ◽  
Warped Extra Dimensions

Abstract We study dark matter interacting via a massive spin-2 mediator. To have a consistent effective theory for the spin-2 particle, we work in a warped extra-dimensional model such that the mediator(s) are the Kaluza-Klein (KK) modes of the 5D graviton. We pay close attention to dark matter annihilations into KK-gravitons. Due to the high energy behavior of longitudinal modes of spin-2 fields, these channels exhibit a tremendous growth at large center of mass energies $$ \sqrt{s} $$ s if only one spin-2 mediator is considered. For the first time, we include the full KK-tower in this dark matter production process and find that this growth is unphysical and cancels once the full field content of the extra-dimensional theory is taken into account. Interestingly, this implies that it is not possible to approximate the results obtained in the full theory with a reduced set of effective interactions once $$ \sqrt{s} $$ s is greater than the first graviton mass. This casts some doubt on the universal applicability of previous studies with spin-2 mediators within an EFT framework and prompts us to revisit the phenomenological allowed parameter space of gravitationally interacting scalar dark matter in warped extra-dimensions.

GRAVITATIONAL BAG EFFECTS ON KALUZA KLEIN AND STRING EXCITATIONS

1989 ◽  
Vol 04 (19) ◽  
pp. 5119-5131 ◽  
Author(s):  
E. I. GUENDELMAN
Keyword(s):  
Extra Dimensions ◽  
Blow Up ◽  
Point Of View ◽  
Spherically Symmetric ◽  
Massive String ◽  
Free Objects ◽  
Higher Dimensional ◽  
Central Regions ◽  
The Masses ◽  
Kaluza Klein

Gravitational Bags are spherically symmetric solutions of higher-dimensional Kaluza Klein (K – K) theories, where the compact dimensions become very large near the center of the geometry, although they are small elsewhere. The K – K excitations therefore become very light when located near the center of this geometry and this appears to affect drastically the naive tower of the masses spectrum of K – K theories. In the context of string theories, string excitations can be enclosed by Gravitational Bags, making them not only lighter, but also localized, as observed by somebody, that does not probe the central regions. Strings, however, can still have divergent sizes, as quantum mechanics seems to demand, since the extra dimensions blow up at the center of the geometry. From a projected 4-D point of view, very massive string bits may lie inside their Schwarzschild radii, as pointed out by Casher, Gravitational Bags however are horizon free objects, so no conflict with macroscopic causality arises if the string excitations are enclosed by Gravitational Bags.

scholarly journals Gauge Theories: From Kaluza–Klein to noncommutative gravity theories

Symmetry ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 856
Author(s):  
George Manolakos ◽  
Pantelis Manousselis ◽  
George Zoupanos
Keyword(s):  
Dimensional Reduction ◽  
Particle Physics ◽  
Extra Dimensions ◽  
Gauge Theories ◽  
Dimensional Theory ◽  
Higher Dimensional ◽  
Coset Spaces ◽  
Gravity Theories ◽  
Physics Model ◽  
Kaluza Klein

First, the Coset Space Dimensional Reduction scheme and the best particle physics model so far resulting from it are reviewed. Then, a higher-dimensional theory in which the extra dimensions are fuzzy coset spaces is described and a dimensional reduction to four-dimensional theory is performed. Afterwards, another scheme including fuzzy extra dimensions is presented, but this time the starting theory is four-dimensional while the fuzzy extra dimensions are generated dynamically. The resulting theory and its particle content is discussed. Besides the particle physics models discussed above, gravity theories as gauge theories are reviewed and then, the whole methodology is modified in the case that the background spacetimes are noncommutative. For this reason, specific covariant fuzzy spaces are introduced and, eventually, the program is written for both the 3-d and 4-d cases.

HIGHER-DIMENSIONAL OPERATORS TO THE RESCUE OF MINIMAL SU(5)

1993 ◽  
Vol 08 (16) ◽  
pp. 1487-1494 ◽  
Author(s):  
BISWAJOY BRAHMACHARI ◽  
P.K. PATRA ◽  
UTPAL SARKAR ◽  
K. SRIDHAR
Keyword(s):  
Quantum Gravity ◽  
Extra Dimensions ◽  
Large Range ◽  
Spontaneous Compactification ◽  
Higher Dimensional ◽  
Gravity Effects ◽  
Proton Lifetime ◽  
Range Of Values ◽  
Kaluza Klein

We consider the modification of the minimal SU(5) Lagrangian due to higher-dimensional operators, arising from quantum gravity effects or from spontaneous compactification of extra dimensions in Kaluza-Klein type theories. Due to these operators the SU (3)c, SU (2)L and U (1)Y couplings do not meet at all at the unification scale, MU, and the magnitudes of the mismatch are directly related to the couplings of the higher-dimensional operators. In particular, we consider five- and six-dimensional operators and show that a large range of values of couplings of these operators are compatible with the latest values of sin 2 θW and as derived from LEP, and also with the experimental constraints on MU coming from proton lifetime.

scholarly journals Kaluza-Klein FIMP dark matter in warped extra-dimensions

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Nicolás Bernal ◽  
Andrea Donini ◽  
Miguel G. Folgado ◽  
Nuria Rius
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Early Universe ◽  
Extra Dimensions ◽  
The Standard Model ◽  
Massive Particles ◽  
Warped Extra Dimensions ◽  
Relic Abundance ◽  
First Time ◽  
Kaluza Klein

Abstract We study for the first time the case in which Dark Matter (DM) is made of Feebly Interacting Massive Particles (FIMP) interacting just gravitationally with the standard model particles in an extra-dimensional Randall-Sundrum scenario. We assume that both the dark matter and the standard model are localized in the IR-brane and only interact via gravitational mediators, namely the graviton, the Kaluza-Klein gravitons and the radion. We found that in the early Universe DM could be generated via two main processes: the direct freeze-in and the sequential freeze-in. The regions where the observed DM relic abundance is produced are largely compatible with cosmological and collider bounds.

EXTRA DIMENSIONS WITH NONTRIVIAL TORSION AND SPINS OF COSMIC STRINGS

2009 ◽  
Vol 24 (14) ◽  
pp. 1147-1157
Author(s):  
ZHEN-BIN CAO ◽  
YI-SHI DUAN
Keyword(s):  
Field Theory ◽  
General Relativity ◽  
Field Strength ◽  
Cosmic String ◽  
Extra Dimensions ◽  
Cosmic Strings ◽  
Higher Dimensional ◽  
Torsion Component ◽  
Einstein’S General Relativity ◽  
Kaluza Klein

As two generalizations of Einstein's general relativity, the nontrivial spacetime torsion and the compact extra dimensions have been largely studied in the literature. In this paper, by combining a torsioned Kaluza–Klein scheme and the field-theory cosmic string theory, we discuss that a higher-dimensional torsion component can be expressed in terms of the usual four-dimensional field strength two-form, and this torsion form can then get trapped into the cores of the cosmic strings and further relate to the intrinsic spins of the strings.

scholarly journals Sum rules for massive spin-2 Kaluza-Klein elastic scattering amplitudes

2019 ◽  
Vol 100 (11) ◽  
Author(s):  
R. Sekhar Chivukula ◽  
Dennis Foren ◽  
Kirtimaan A. Mohan ◽  
Dipan Sengupta ◽  
Elizabeth H. Simmons
Keyword(s):  
Elastic Scattering ◽  
Scattering Amplitudes ◽  
Sum Rules ◽  
Massive Spin ◽  
Kaluza Klein

Principles of Quantum-like Evolution

2019 ◽  
Vol 26 (02) ◽  
pp. 1950007
Author(s):  
Andrzej Wichert
Keyword(s):  
Markov Chain ◽  
Probability Distribution ◽  
Tensor Product ◽  
Open System ◽  
Stochastic Matrix ◽  
Chaotic Behaviour ◽  
Quantum Cognition ◽  
Higher Dimensional ◽  
The Matrix

We present a case study of quantum-like probabilities that are motivated by quantum cognition. We introduce quantum-like evolution that is l2 norm preserving but in which the matrix does not need to be unitary. We show how to map any 2 × 2 stochastic matrix to an l2 norm preserving balanced phase matrix that maps real vectors of length one into complex vectors of length one. Quantum-like evolution can simulate a probability distribution of open system in which the operator is not unitary but norm preserving. Such a kind of behaviour is studied in quantum cognition. By tensor product higher dimensional balanced phase matrices can be built. Quantum-like evolution can simulate either unitary open one by coding the phase of input vector into the phase of a balanced phase matrix, a Markov chain or an alternative evolution that can lead to fixed, periodic or chaotic behaviour resulting in strange oscillations.

Dimensionality

1983 ◽  
Vol 310 (1512) ◽  
pp. 337-346 ◽  
Keyword(s):  
Fractal Dimension ◽  
Dimensional Reduction ◽  
Mathematical Properties ◽  
Higher Dimensional ◽  
Dimensional Gravity ◽  
Low Dimensional ◽  
Physical Laws ◽  
Dimensions Of Space ◽  
Constants Of Nature ◽  
Kaluza Klein

We examine the role played by the dimensions of space and space-time in determining the form of various physical laws and constants of Nature. Low dimensional manifolds are also seen to possess special mathematical properties. The concept of fractal dimension is introduced and we discuss the recent renaissance of Kaluza-Klein theories obtained by dimensional reduction from higher dimensional gravity or supergravity theories. A formulation of the anthropic principle is suggested.

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