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Phenomenology of neutrino properties, unification, and Higgs couplings beyond the Standard Model
KTH, School of Engineering Sciences (SCI), Physics, Theoretical Particle Physics.
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The vast majority of experiments in particle physics can be described by the Standard Model of particle physics (SM). However, there are indications for physics beyond it. The only experimentally demonstrated problem of the model is the difficulty to describe neutrino masses and leptonic mixing. There is a plethora of models that try to describe these phenomena and this thesis investigates several possibilities for new models, both full theories and effective frameworks.

 

The values of the parameters in a model are dependent on the energy scale and we say that the parameters run. The exact behavior of the running depends on the model and it provides a signature of the model. For a model defined at high energies it is necessary to run the parameters down to the electroweak scale in order to perform a comparison to the known values of observed quantities. In this thesis, we discuss renormalization group running in the context of extra dimensions and we provide an upper limit on the cutoff scale. We perform renormalization group running in two versions of a non-supersymmetric SO(10) model and we show that the SM parameters can be accommodated in both versions. In addition, we perform the running for the gauge couplings in a large set of radiative neutrino mass models and conclude that unification is possible in some of them.

 

The Higgs boson provides new possibilities to study physics beyond the SM. Its properties have to be tested with extremely high precision before it could be established whether the particle is truly the SM Higgs boson or not. In this thesis, we perform Bayesian parameter inference and model comparison. For models where the magnitude of the Higgs couplings is varied, we show that the SM is favored in comparison to all other models. Furthermore, we discuss lepton flavor violating processes in the context of the Zee model. We find that these can be sizeable and close to the experimental limits.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. , p. 98
Series
TRITA-FYS, ISSN 0280-316X ; 2017:10
Keywords [en]
Effective field theories, neutrino physics, extra dimensions, universal extra dimensions, Higgs physics, renormalization group running, Bayesian statistics, grand unified theories
National Category
Subatomic Physics
Research subject
Physics
Identifiers
URN: urn:nbn:se:kth:diva-202311ISBN: 978-91-7729-298-2 (print)OAI: oai:DiVA.org:kth-202311DiVA, id: diva2:1075735
Public defence
2017-03-24, FB53, Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20170221

Available from: 2017-02-21 Created: 2017-02-20 Last updated: 2017-02-23Bibliographically approved
List of papers
1. Running of neutrino parameters and the Higgs self-coupling in a six-dimensional UED model
Open this publication in new window or tab >>Running of neutrino parameters and the Higgs self-coupling in a six-dimensional UED model
2013 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 718, no 3, p. 1002-1007Article in journal (Refereed) Published
Abstract [en]

We investigate a six-dimensional universal extra-dimensional model in the extension of an effective neutrino mass operator. We derive the β-functions and renormalization group equations for the Yukawa couplings, the Higgs self-coupling, and the effective neutrino mass operator in this model. Especially, we focus on the renormalization group running of physical parameters such as the Higgs self-coupling and the leptonic mixing angles. The recent measurements of the Higgs boson mass by the ATLAS and CMS Collaborations at the LHC as well as the current three-flavor global fits of neutrino oscillation data have been taken into account. We set a bound on the six-dimensional model, using the vacuum stability criterion, that allows five Kaluza-Klein modes only, which leads to a strong limit on the cutoff scale. Furthermore, we find that the leptonic mixing angle θ12 shows the most sizeable running, and that the running of the angles θ13 and θ23 are negligible. Finally, it turns out that the findings in this six-dimensional model are comparable with what is achieved in the corresponding five-dimensional model, but the cutoff scale is significantly smaller, which means that it could be detectable in a closer future.

Place, publisher, year, edition, pages
Elsevier, 2013
Keywords
Mass Operator Renormalization, Extra Dimensions, Standard Model, Lhc, Particle, Boson
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-118106 (URN)10.1016/j.physletb.2012.11.042 (DOI)000314259500033 ()2-s2.0-84871623486 (Scopus ID)
Funder
Swedish Research Council, 621-2011-3985
Note

QC 20130212

Available from: 2013-02-20 Created: 2013-02-12 Last updated: 2017-12-06Bibliographically approved
2. Bayesian Model comparison of Higgs couplings
Open this publication in new window or tab >>Bayesian Model comparison of Higgs couplings
2015 (English)In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 91, no 7, article id 075008Article in journal (Refereed) Published
Abstract [en]

We investigate the possibility of contributions from physics beyond the Standard Model (SM) to the Higgs couplings, in the light of the LHC data. The work is performed within an interim framework where the magnitude of the Higgs production and decay rates are rescaled through Higgs coupling scale factors. We perform Bayesian parameter inference on these scale factors, concluding that there is good compatibility with the SM. Furthermore, we carry out a Bayesian model comparison on all models where any combination of scale factors can differ from their SM values and find that typically models with fewer free couplings are strongly favored. We consider the evidence that each coupling individually equals the SM value, making the minimal assumptions on the other couplings. Finally, we make a comparison of the SM against a single "not-SM" model and find that there is moderate to strong evidence for the SM.

Keywords
Massless Particles, Broken Symmetries, Atlas Detector, Lhc, Boson, Curvature, Cosmology, Inference, Efficient, Tevatron
National Category
Subatomic Physics
Research subject
Physics
Identifiers
urn:nbn:se:kth:diva-154047 (URN)10.1103/PhysRevD.91.075008 (DOI)000352786500008 ()
Funder
Swedish Research Council, 621-2011-3985EU, FP7, Seventh Framework Programme, PITN-GA-2011-289442
Note

QC 20141020

Available from: 2014-10-13 Created: 2014-10-13 Last updated: 2017-12-05Bibliographically approved
3. Unification of gauge couplings in radiative neutrino mass models
Open this publication in new window or tab >>Unification of gauge couplings in radiative neutrino mass models
2016 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 9, article id 111Article in journal (Refereed) Published
Abstract [en]

We investigate the possibility of gauge coupling uni fi cation in various radiative neutrino mass models, which generate neutrino masses at one-and/or two-loop level. Renormalization group running of gauge couplings is performed analytically and numerically at one-and two-loop order, respectively. We study three representative classes of radiative neutrino mass models: (I) minimal ultraviolet completions of the dimension-7 Delta L = 2 operators which generate neutrino masses at one-and/or two-loop level without and with dark matter candidates, (II) models with dark matter which lead to neutrino masses at one-loop level and (III) models with particles in the adjoint representation of SU(3). In class (I), gauge couplings unify in a few models and adding dark matter amplifies the chances for uni fi cation. In class (II), about a quarter of the models admits gauge coupling uni fi cation. In class (III), none of the models leads to gauge coupling uni fi cation. Regarding the scale of uni fi cation, we find values between 10(14) GeV and 10(16) GeV for models belonging to class (I) without dark matter, whereas models in class (I) with dark matter as well as models of class (II) prefer values in the range 5.10(10) - 5.10(14) GeV.

Place, publisher, year, edition, pages
Springer, 2016
Keywords
GUT, Renormalization Group, Effective field theories, Neutrino physics
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-194473 (URN)10.1007/JHEP09(2016)111 (DOI)000384605700001 ()2-s2.0-84988514181 (Scopus ID)
Funder
Swedish Research Council, 621-2011-3985
Note

QC 20161031

Available from: 2016-10-31 Created: 2016-10-28 Last updated: 2017-11-29Bibliographically approved
4. Renormalization Group Running of Fermion Observables in an Extended Non-Supersymmetric SO(10) Model
Open this publication in new window or tab >>Renormalization Group Running of Fermion Observables in an Extended Non-Supersymmetric SO(10) Model
(English)Manuscript (preprint) (Other academic)
Abstract [en]

We investigate the renormalization group evolution of fermion masses, mixings and quartic scalar Higgs self-couplings in an extended non-supersymmetric SO(10) model, where the Higgs sector contains the 10H, 120H, and 126H representations. The group SO(10) is spontaneously broken at the GUT scale to the Pati-Salam group and subsequently to the Standard Model (SM) at an intermediate scale MI. We explicitly take into account the effects of the change of gauge groups in the evolution. In particular, we derive the renormalization group equations for the different Yukawa couplings. We find that the computed physical fermion observables can be successfully matched to the experimental measured values at the electroweak scale. Using the same Yukawa couplings at the GUT scale, the measured values of the fermion observables cannot be reproduced with a SM-like evolution, leading to differences in the numerical values up to around 80 %. Furthermore, a similar evolution can be performed for a minimal SO(10) model, where the Higgs sector consists of the 10H and 126H representations only, showing an equally good potential to describe the low-energy fermion observables. Finally, for both the extended and the minimal SO(10) models, we present predictions for the three Dirac and Majorana CP-violating phases as well as three effective neutrino mass parameters.

National Category
Subatomic Physics
Research subject
Physics
Identifiers
urn:nbn:se:kth:diva-202305 (URN)
Note

QC 20170221

Available from: 2017-02-20 Created: 2017-02-20 Last updated: 2017-02-21Bibliographically approved
5. Full parameter scan of the Zee model: exploring Higgs lepton flavor violation
Open this publication in new window or tab >>Full parameter scan of the Zee model: exploring Higgs lepton flavor violation
(English)Manuscript (preprint) (Other academic)
Abstract [en]

We study the general Zee model, which includes an extra Higgs scalar doublet and a new singly-charged scalar singlet. Neutrino masses are generated at one-loop level, and in order to describe leptonic mixing, both the Standard Model and the extra Higgs scalar doublets need to couple to leptons (in a type-III two-Higgs doublet model), which necessarily generates large lepton flavor violating signals, also in Higgs decays. Imposing all relevant phenomenological constraints and performing a full numerical scan of the parameter space, we find that both normal and inverted neutrino mass orderings can be fitted, although the latter is disfavored with respect to the former. In fact, inverted ordering can only be accommodated if θ23 turns out to be in the first octant. A branching ratio for h→τμ of up to 10−2 is allowed, but it could be as low as 10−6. In addition, if future expected sensitivities of τ→μγ are achieved, normal ordering can be completely tested. Also, μeconversion is expected to strongly reduce the allowed parameter space, excluding completely inverted ordering. Furthermore, non-standard neutrino interactions are found to be smaller than 10−6, which is well below future experimental sensitivity. Finally, the results of our scan indicate that the masses of the additional scalars have to be below 2.5 TeV, and typically they are lower than that and therefore within the reach of the LHC and future colliders.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-202306 (URN)
Note

QC 20170221

Available from: 2017-02-20 Created: 2017-02-20 Last updated: 2017-02-21Bibliographically approved

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