Aspects of symmetry breaking in supersymmetric models

Supersymmetry is a widely used extension of the Standard Model of particle physics. It extends the Standard Model by adding a symmetry between bosonic and fermionic particles and introduces superpartners -- particles with similar quantum numbers but opposite spin statistics -- for each of the Standard Model fields. The scalar partners of Standard Model particles allow for the construction of Lorentz and gauge invariant terms in the Lagrangian that break symmetries (or near symmetries) of the Standard Model, such as CP, flavor, baryon number, and lepton number. This presents both a challenge in explaining the absence of large symmetry breaking effects, and an opportunity for indirect discovery of Supersymmetry in precision experiments. In the Standard Model the mentioned symmetries are accidental and unrelated. In a supersymmetric model they must be specifically reinstated and dynamically broken, or be otherwise constrained. As a consequence, these symmetries can become linked via the specifics of their breaking mechanisms. The subject of this thesis is the construction of models where this happens and the consequent relationships between symmetry breaking observables as well as the effects on other phenomenologically interesting quantities, such as Dark Matter and neutrino masses. The first part of the thesis is an introduction to the Standard Model, and the second part details the specifics of supersymmetric model building. The third part introduces the subject matter of the papers included in this thesis and presents some of the papers' key findings.Hiukkasfysiikassa on käytössä 60-luvulla kehitetty niin kutsuttu stadardimalli, joka puolustaa paikkansa yhtenä tieteen parhaimmin toimivana teoriana. Standardimalli on selvinnyt vuosikymmenien ajan lukuistista kokeista, joilla sen paikkansapitävyyttä on testattu. Tiedämme kuitenkin että standardimalli ei voi olla lopullinen, niin sanottu "kaiken teoria", sillä se ei esimerkiksi kuvaa gravitaatiota. Lisäksi standardimalli näyttää vaativan tiettyjen laskennallisten suureiden luonnottman tarkka kumoutumista. On siis oletettavaa, että jollain tasolla standardimalli on vain matalan energian approksimaatio jostain toisesta teoriasta. Supersymmetria on tällä hetkellä laajimmin käytössä oleva standardimallin laajennus, joka pyrkii korjaamaan joitakin standardimallin ongelmia. Supersymmetria lisää malliin jokaiselle hiukkaselle supersymmetrisen parin sekä suuren määrän uusia vuorovaikutuksia, joissa nämä uudet hiukkaset ovat osallisena. Suuri osa näistä uusista vuorovaikutuksista rikkoo standardimallissa voimassa olevia symmetrioita mikä asettaa tiukkoja rajoituksia supersymmetrisen mallin tietyille parametreille. Tämä väitöskirja tutkii kuinka joidenkin symmetrioiden rikkomiset ja rikkomismekanismit voivat liittyä toisiinsa supersymmetrisessä mallissa ja kuinka nämä symmetriarikot vaikuttavat erilaisiin mitattavissa oleviin suureisiin

A large Muon Electric Dipole Moment from Flavor?

We study the prospects and opportunities of a large muon electric dipole moment (EDM) of the order (10^{-24} - 10^{-22}) ecm. We investigate how natural such a value is within the general minimal supersymmetric extension of the Standard Model with CP violation from lepton flavor violation in view of the experimental constraints. In models with hybrid gauge-gravity mediated supersymmetry breaking a large muon EDM is indicative for the structure of flavor breaking at the Planck scale, and points towards a high messenger scale.Comment: 12 pages, 12 figures. v3: References and Eq 28 fixed; conclusions unchange

Comparison of neutralino and sneutrino dark matter in a model with spontaneous CP violation

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