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 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.

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.

scholarly journals Does Compton–Schwarzschild duality in higher dimensions exclude TeV quantum gravity?

2018 ◽  
Vol 27 (16) ◽  
pp. 1930001 ◽  
Author(s):  
Matthew J. Lake ◽  
Bernard Carr
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Wave Function ◽  
Quantum Gravity ◽  
Extra Dimensions ◽  
Planck Length ◽  
Compton Wavelength ◽  
Planck Mass ◽  
Higher Dimensional ◽  
Spatial Dimensions

In three spatial dimensions, the Compton wavelength [Formula: see text]) and Schwarzschild radius [Formula: see text]) are dual under the transformation [Formula: see text], where [Formula: see text] is the Planck mass. This suggests that there could be a fundamental link — termed the Black Hole Uncertainty Principle or Compton–Schwarzschild correspondence — between elementary particles with [Formula: see text] and black holes in the [Formula: see text] regime. In the presence of [Formula: see text] extra dimensions, compactified on some scale [Formula: see text] exceeding the Planck length [Formula: see text], one expects [Formula: see text] for [Formula: see text], which breaks this duality. However, it may be restored in some circumstances because the effective Compton wavelength of a particle depends on the form of the [Formula: see text]-dimensional wave function. If this is spherically symmetric, then one still has [Formula: see text], as in the [Formula: see text]-dimensional case. The effective Planck length is then increased and the Planck mass reduced, allowing the possibility of TeV quantum gravity and black hole production at the LHC. However, if the wave function of a particle is asymmetric and has a scale [Formula: see text] in the extra dimensions, then [Formula: see text], so that the duality between [Formula: see text] and [Formula: see text] is preserved. In this case, the effective Planck length is increased even more but the Planck mass is unchanged, so that TeV quantum gravity is precluded and black holes cannot be generated in collider experiments. Nevertheless, the extra dimensions could still have consequences for the detectability of black hole evaporations and the enhancement of pair-production at accelerators on scales below [Formula: see text]. Though phenomenologically general for higher-dimensional theories, our results are shown to be consistent with string theory via the minimum positional uncertainty derived from [Formula: see text]-particle scattering amplitudes.

SAVE SU(5) GUT WITH FOURTH RANK TENSOR HIGGS IN THE PRESENCE OF SPONTANEOUS COMPACTIFICATION

1986 ◽  
Vol 01 (02) ◽  
pp. 119-124 ◽  
Author(s):  
FANG-XIAO DONG ◽  
TUNG-SHENG TU ◽  
PEI-YOU XUE
Keyword(s):  
Higgs Field ◽  
Spontaneous Compactification ◽  
Weak Mixing Angle ◽  
Mixing Angle ◽  
Rank Tensor ◽  
Higher Dimensional ◽  
Proton Lifetime ◽  
Standard Value ◽  
Models Of Gravity ◽  
Good Agreement

The properties of SU(5) GUT with a 75-dimensional Higgs field [Formula: see text] are discussed in the presence of spontaneous compactification. We find that the value of the weak mixing angle at the weak scale Mw is sin2 θw(Mw)~0.22 which is in good agreement with experiments. The proton lifetime is longer by two orders of magnitude than its standard value. If we assume that SU(5) GUT arises from higher dimensional models of gravity with extra dimensions compactified, then spontaneous compactification can save SU(5) GUT.

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.

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.

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