Unitarity in Gauge Symmetry Breaking on an Orbifold

Abe, Yoshikazu; Haba, Naoyuki; Higashide, Y.; Kobayashi, Kazuo; Matsunaga, Mamoru

doi:10.1143/ptp.109.831

Cited by 30 publications

(19 citation statements)

References 7 publications

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“…We note that in several models of orbifold/boundary symmetry breaking, it has been shown that the longitudinal gauge boson scattering etc. are indeed unitarized by taking into accout Kaluza-Klein mode contributions [12,13,14,15,16,17,18]. Therefore, it would be expected that the bulk gauge boson scattering is unitarized in such a region of our model (above the KK scale but lower than the five-dimensional cut-off scale) by taking into account all the relevant KK modes.…”

Section: Summary and Discussionmentioning

confidence: 94%

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Haba¹,

Oda²,

Takahashi³

2011

Acta Phys. Pol. B

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We propose a simple five-dimensional extension of the Standard Model (SM) without any Higgs potential nor any extra fields. A Higgs doublet lives in the bulk of a flat line segment and its boundary condition is Dirichlet at the ends of the line, which causes the electroweak symmetry breaking without Higgs potential. The vacuum expectation value of the Higgs is induced from the Dirichlet boundary condition which is generally allowed in higher dimensional theories. The lightest physical Higgs has non-flat profile in the extra dimension even though the vacuum expectation value is flat. As a consequence, we predict a maximal top Yukawa deviation (no coupling between top and Higgs) for the brane-localized fermion and a small deviation, a multiplication of 2 √ 2/π 0.9 to the Yukawa coupling, for the bulk fermion. The latter is consistent with the electroweak precision data within 90% C.L. for 430 GeV m KK 500 GeV.

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Section: Summary and Discussionmentioning

confidence: 94%

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Haba¹,

Oda²,

Takahashi³

2011

Acta Phys. Pol. B

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“…The case of a single compact extra dimension has been studied previously in Refs. [22][23][24][25][26][27].…”

Section: Yang-mills Theorymentioning

confidence: 99%

Unitarization from geometry

Bonifacio

Hinterbichler

2019

J. High Energ. Phys.

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We study the perturbative unitarity of scattering amplitudes in general dimensional reductions of Yang-Mills theories and general relativity on closed internal manifolds. For the tree amplitudes of the dimensionally reduced theory to have the expected high-energy behavior of the higherdimensional theory, the masses and cubic couplings of the Kaluza-Klein states must satisfy certain sum rules that ensure there are nontrivial cancellations between Feynman diagrams. These sum rules give constraints on the spectra and triple integrals of eigenfunctions of Laplacian operators on the internal manifold and can be proven directly using Hodge and eigenfunction decompositions. One consequence of these constraints is that there is an upper bound on the ratio of consecutive eigenvalues of the scalar Laplacian on closed Ricci-flat manifolds with special holonomy. This gives a sharp bound on the allowed gaps between Kaluza-Klein excitations of the graviton that also applies to Calabi-Yau compactifications of string theory.

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“…8 Some related works are found in Refs. [54][55][56][57][58][59][60][61]. 9 The smallness of Q is not an unnatural thing because they are resultant values derived from the two input parameters L ± , for which the dimensionless values are within O(10) as in Eq.…”

Section: Cp Phase In the Ckm Matrixmentioning

confidence: 99%

CPphase from twisted Higgs vacuum expectation value in extra dimension

2013

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We propose a new mechanism for generating a CP phase via Higgs a vacuum expectation value originating from geometry of an extra dimension. A twisted boundary condition is the key to produce an extra-dimension coordinate-dependent vacuum expectation value, which contains a CP phase degree of freedom and can be a new source of a CP phase in higher-dimensional gauge theories. As an illustrative example, we apply our mechanism to a five-dimensional gauge theory with point interactions and show that our mechanism can dynamically produce a nontrivial CP -violating phase with electroweak symmetry breaking, even though the five-dimensional model does not include any CP -violating phases of Yukawa couplings in the five-dimensional Lagrangian because of a single generation of five-dimensional fermions. We apply our mechanism to a model with point interactions, which has no source of CP -violating phases in the couplings of the higher-dimensional action, and show that a nontrivial CP phase dynamically appears.

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Unitarity in Gauge Symmetry Breaking on an Orbifold

Cited by 30 publications

References 7 publications

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Unitarization from geometry

CPphase from twisted Higgs vacuum expectation value in extra dimension

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