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Particle Phenomenology of Compact Extra Dimensions
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is an investigation of the subject of extra dimensions in particle physics. In recent years, there has been a large interest in this subject. In particular, a number of models have been suggested that provide solutions to some of the problem with the current Standard Model of particle physics. These models typically give rise to experimental signatures around the TeV energy scale, which means that they could be tested in the next generation of high-energy experiments, such as the LHC. Among the most important of these models are the universal extra dimensions model, the large extra dimensions model by Arkani-Hamed, Dimopolous, and Dvali, and models where right-handed neutrinos propagate in the extra dimensions.

In the thesis, we study phenomenological aspects of these models, or simple modifications of them. In particular, we focus on Kaluza–Klein dark matter in universal extra dimensions models, different aspects of neutrino physics in higher dimensions, and collider phenomenology of extra dimensions. In addition, we consider consequences of the enhanced renormalization group running of physical parameters in higher-dimensional models.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , xiv, 98 p.
Series
Trita-FYS, ISSN 0280-316X ; 2012:16
Keyword [en]
Higher-dimensional quantum field theories, universal extra dimensions, Arkani-Hamed–Dimopolous–Dvali (ADD) model, hierarchy problem, Kaluza– Klein dark matter, neutrino mass, seesaw mechanism, leptonic mixing, renormalization group running, collider phenomenology, Large Hadron Collider
National Category
Subatomic Physics
Identifiers
URN: urn:nbn:se:kth:diva-93749ISBN: 978-91-7501-305-3 (print)OAI: oai:DiVA.org:kth-93749DiVA: diva2:523633
Public defence
2012-05-11, Sal FB53, Albanova, Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20120427Available from: 2012-04-27 Created: 2012-04-25 Last updated: 2012-04-27Bibliographically approved
List of papers
1. Neutrinos from Kaluza-Klein dark matter in the Sun
Open this publication in new window or tab >>Neutrinos from Kaluza-Klein dark matter in the Sun
2010 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, Vol. 2010, no 01, 018- p.Article in journal (Refereed) Published
Abstract [en]

We investigate indirect neutrino signals from annihilations of Kaluza-Klein dark matter in the Sun. Especially, we examine a five- as well as a six-dimensional model, and allow for the possibility that boundary localized terms could affect the spectrum to give different lightest Kaluza-Klein particles, which could constitute the dark matter. The dark matter candidates that are interesting for the purpose of indirect detection of neutrinos are the first Kaluza-Klein mode of the U(1) gauge boson and the neutral component of the SU(2) gauge bosons. Using the DarkSUSY and WimpSim packages, we calculate muon fluxes at an Earth-based neutrino telescope, such as IceCube. For the five-dimensional model, the results hat we obtained agree reasonably well with the results that have previously been presented in the literature, whereas for the six-dimensional model, we find that, at tree-level, the results are the same as for the five-dimensional model. Finally, if the first Kaluza-Klein mode of the U(1) gauge boson constitutes the dark matter, IceCube can constrain the parameter space. However, in the case that the neutral component of the SU(2) gauge bosons is the LKP, the signal is too weak to be observed.

Place, publisher, year, edition, pages
IOP Publishing / SISSA, 2010
Keyword
dark matter theory, extra dimensions, neutrino astronomy
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-31713 (URN)10.1088/1475-7516/2010/01/018 (DOI)000289245200008 ()
Funder
Swedish Research Council, 623-2007-8066Swedish Research Council, 621-2005-3588Swedish Research Council, 621-2008-4210
Note
QC 20110324Available from: 2011-06-21 Created: 2011-03-24 Last updated: 2012-04-27Bibliographically approved
2. Monoenergetic gamma rays from nonminimal Kaluza-Klein dark matter annihilations
Open this publication in new window or tab >>Monoenergetic gamma rays from nonminimal Kaluza-Klein dark matter annihilations
2012 (English)In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 85, no 4, 043524- p.Article in journal (Refereed) Published
Abstract [en]

We investigate monoenergetic gamma-ray signatures from annihilations of dark matter comprised of Z(1), the first Kaluza-Klein (KK) excitation of the Z boson in a nonminimal universal extra dimensions (UED) model. The self interactions of the non-Abelian Z(1) gauge boson give rise to a large number of contributing Feynman diagrams that do not exist for annihilations of the Abelian gauge boson B-1, which is the standard Kaluza-Klein dark matter (KKDM) candidate. We find that the annihilation rate is indeed considerably larger for the Z(1) than for the B-1. Even though relic density calculations indicate that the mass of the Z(1) should be larger than the mass of the B-1, the predicted monoenergetic gamma fluxes are of the same order of magnitude. We compare our results to existing experimental limits, as well as to future sensitivities, for image air Cherenkov telescopes, and we find that the limits are reached already with a moderately large boost factor. The realistic prospects for detection depend on the experimental energy resolution.

Place, publisher, year, edition, pages
The American Physical Society, 2012
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:kth:diva-50382 (URN)10.1103/PhysRevD.85.043524 (DOI)000300571500006 ()2-s2.0-84857700861 (Scopus ID)
Funder
Swedish Research Council, 621-2008-4210
Note
QC 20111208Available from: 2012-02-23 Created: 2011-12-05 Last updated: 2017-12-08Bibliographically approved
3. Continuum photon spectrum from Z1Z1 annihilations in universal extra dimensions
Open this publication in new window or tab >>Continuum photon spectrum from Z1Z1 annihilations in universal extra dimensions
2012 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 706, no 4-5, 329-332 p.Article in journal (Refereed) Published
Abstract [en]

We calculate the continuum photon spectrum from the pair annihilation of a Z1 LKP in non-minimal universal extra dimensions. We find that, due to the preferred annihilation into W+ W- pairs, the continuum flux of collinear photons is relatively small compared to the standard case of the B1 as the LKP. This conclusion applies in particular to the spectral endpoint, where also the additional fermionic contributions are not large enough to increase the flux significantly. When searching for the line signal originating from Z1 Z1 annihilations, this is actually a perfect situation, since the continuum signal can be regarded as background to the smoking gun signature of a peak in the photon flux at an energy that is nearly equal to the mass of the dark matter particle. This signal, in combination with (probably) a non-observation of the continuum signal at lower photon energies, constitutes a perfect handle to probe the hypothesis of the Z1 LKP being the dominant component of the dark matter observed in the Universe.

Place, publisher, year, edition, pages
Elsevier B.V., 2012
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:kth:diva-50386 (URN)10.1016/j.physletb.2011.11.018 (DOI)000299756800011 ()2-s2.0-84155165683 (Scopus ID)
Funder
Swedish Research Council, 621-2008-4210
Note

This is the author’s version of a work that was accepted for publication in Physics Letters B. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Physics Letters B, VOL 706, ISSUE 4-5, (15 November 2011) DOI:10.1016/j.physletb.2011.11.018. QC 20120223  Correction ISI: 000306305000041  Doi: 10.1016/j.physletb.2012.05.059

Available from: 2012-02-23 Created: 2011-12-05 Last updated: 2017-12-08Bibliographically approved
4. Higgs Kaluza–Klein dark matter in universal extra dimensions
Open this publication in new window or tab >>Higgs Kaluza–Klein dark matter in universal extra dimensions
2008 (English)Manuscript (preprint) (Other academic)
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-93796 (URN)
Note
QS 2012Available from: 2012-04-27 Created: 2012-04-27 Last updated: 2012-04-27Bibliographically approved
5. Signatures from an extra-dimensional seesaw model
Open this publication in new window or tab >>Signatures from an extra-dimensional seesaw model
2010 (English)In: Physical Review D, ISSN 1550-7998, Vol. 82, no 4, 045023- p.Article in journal (Refereed) Published
Abstract [en]

We study the generation of small neutrino masses in an extra-dimensional model, where singlet fermions are allowed to propagate in the extra dimension, while the standard model particles are confined to a brane. Motivated by the fact that extra-dimensional models are nonrenormalizable, we truncate the Kaluza-Klein towers at a maximal Kaluza-Klein number. This truncation, together with the structure of the bulk Majorana mass term, motivated by the Sherk-Schwarz mechanism, implies that the Kaluza-Klein modes of the singlet fermions pair to form Dirac fermions, except for a number of unpaired Majorana fermions at the top of each tower. These heavy Majorana fermions are the only sources of lepton number breaking in the model, and similarly to the type-I seesaw mechanism, they naturally generate small masses for the left-handed neutrinos. The lower Kaluza-Klein modes mix with the light neutrinos, and the mixing effects are not suppressed with respect to the light-neutrino masses. Compared to conventional fermionic seesaw models, such mixing can be more significant. We study the signals of this model at the Large Hadron Collider, and find that the current low-energy bounds on the nonunitarity of the leptonic mixing matrix are strong enough to exclude an observation.

Place, publisher, year, edition, pages
The American Physical Society, 2010
Keyword
NEUTRINO OSCILLATIONS, PHENOMENOLOGICAL IMPLICATIONS, CP-VIOLATION, MASSES, UNIVERSE, MIXINGS, PHYSICS, LHC
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-26840 (URN)10.1103/PhysRevD.82.045023 (DOI)000281070800010 ()
Funder
EU, FP7, Seventh Framework ProgrammeSwedish Research Council, 621-2008-4210
Note
QC 20101206 Denna artikel är en granskad och publicerad version av manuskriptet "Non-unitary neurtino mixing from an extra-dimensional seesaw model" som hör till avhandlingen "Astrophysical and Collider Signatures of Extra Dimensions". This article is a peer-reviewed and published version of the manuscript "Non-unitary neurtino mixing from an extra-dimensional seesaw model" which is a part of the doctoral dissertation "Astrophysical and Collider Signatures of Extra Dimensions".Available from: 2011-06-17 Created: 2010-11-29 Last updated: 2012-04-27Bibliographically approved
6. Renormalization group running of the neutrino mass operator in extra dimensions
Open this publication in new window or tab >>Renormalization group running of the neutrino mass operator in extra dimensions
2011 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 2011, no 04, 052- p.Article in journal (Refereed) Published
Abstract [en]

We study the renormalization group (RG) running of the neutrino masses and the leptonic mixing parameters in two different extra-dimensional models, namely, the Universal Extra Dimensions (UED) model and a model, where the Standard Model (SM) bosons probe an extra dimension and the SM fermions are confined to a four-dimensional brane. In particular, we derive the beta function for the neutrino mass operator in the UED model. We also rederive the beta function for the charged-lepton Yukawa coupling, and confirm some of the existing results in the literature. The generic features of the RG running of the neutrino parameters within the two models are analyzed and, in particular, we observe a power-law behavior for the running. We note that the running of the leptonic mixing angle theta(12) can be sizable, while the running of theta(23) and theta(13) is always negligible. In addition, we show that the tri-bimaximal and the bimaximal mixing patterns at a high-energy scale are compatible with low-energy experimental data, while a tri-small mixing pattern is not. Finally, we perform a numerical scan over the low-energy parameter space to infer the high-energy distribution of the parameters. Using this scan, we also demonstrate how the high-energy theta(12) is correlated with the smallest neutrino mass and the Majorana phases.

Place, publisher, year, edition, pages
Springer-Verlag, 2011
Keyword
Neutrino Physics, Field Theories in Higher Dimensions, Renormalization Group
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-34658 (URN)10.1007/JHEP04(2011)052 (DOI)000290331700052 ()2-s2.0-80053266818 (Scopus ID)
Funder
EU, FP7, Seventh Framework ProgrammeSwedish Research Council, 621-2008-4210EU, European Research Council, MANITOP
Note
QC 20110627Available from: 2011-07-01 Created: 2011-06-13 Last updated: 2017-12-11Bibliographically approved
7. RG running in a minimal UED model in light of recent LHC Higgs mass bounds
Open this publication in new window or tab >>RG running in a minimal UED model in light of recent LHC Higgs mass bounds
2012 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 712, no 4-5, 419-424 p.Article in journal (Refereed) Published
Abstract [en]

We study how the recent ATLAS and CMS Higgs mass bounds affect the renormalization group running of the physical parameters in universal extra dimensions. Using the running of the Higgs self-coupling constant, we derive bounds on the cutoff scale of the extra-dimensional theory itself. We show that the running of physical parameters, such as the fermion masses and the CKM mixing matrix, is significantly restricted by these bounds. In particular, we find that the running of the gauge couplings cannot be sufficient to allow gauge unification at the cutoff scale.

Place, publisher, year, edition, pages
Elsevier, 2012
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-79444 (URN)10.1016/j.physletb.2012.05.029 (DOI)000305378200016 ()2-s2.0-84861481123 (Scopus ID)
Funder
Swedish Research Council, 621-2008-4210Swedish Research Council, 621-2011-3985
Note

Updated from manuscript to article in journal.

Previous manuscript title: RG running in UEDs in light of recent LHC Higgs mass bounds

QC 20120223

Available from: 2012-02-23 Created: 2012-02-09 Last updated: 2017-12-07Bibliographically approved
8. Searches for hyperbolic extra dimensions at the LHC
Open this publication in new window or tab >>Searches for hyperbolic extra dimensions at the LHC
2008 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 2008, no 08, 077- p.Article in journal (Refereed) Published
Abstract [en]

We investigate a model of large extra dimensions where the internal space has the geometry of a hyperbolic disc. Compared with the ADD model, this model provides a more satisfactory solution to the hierarchy problem between the electroweak scale and the Planck scale, and it also avoids constraints from astrophysics. In general, a novel feature of this model is that the physical results depend on the position of the brane in the internal space, and in particular, the signal almost disappears completely if the brane is positioned at the center of the disc. Since there is no known analytic form of the Kaluza-Klein spectrum for our choice of geometry, we obtain a spectrum based on a combination of approximations and numerical computations. We study the possible signatures of our model for hadron colliders, especially the LHC, where the most important processes are the production of a graviton together with a hadronic jet or a photon. We find that the signals are similar to those of the ADD model, regarding both qualitative behavior and strength. For the case of hadronic jet production, it is possible to obtain relatively strong signals, while for the case of photon production, this is much more difficult.

Place, publisher, year, edition, pages
IOP Publishing, 2008
Keyword
large extra dimensions, hadronic colliders, space dimensions, millimeter, hierarchy, gravity, signals
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-17796 (URN)10.1088/1126-6708/2008/08/077 (DOI)000258917400032 ()2-s2.0-54749115150 (Scopus ID)
Funder
Swedish Research Council, 621-2005-3588
Note
QC 20100525Available from: 2011-06-21 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved

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