@phdthesis{Franke1995,
  author    = {Franke, Fabian},
  title     = {Produktion und Zerfall von Neutralinos im Nichtminimalen Supersymmetrischen Standardmodell},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-25666},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {1995},
  abstract  = {Das Ziel der vorliegenden Arbeit ist eine umfassende Analyse von Erzeugung und anschließenden Zerf{\"a}llen von Neutralinos im Nichtminimalen Supersymmetrischen Standardmodell (NMSSM) speziell f{\"u}r den n{\"a}chsten verf{\"u}gbaren Elektron-Positron-Speicherring LEP2 am CERN mit einer voraussichtlichen Schwerpunktsenergie von 190 GeV. Das NMSSM ist die einfachste Erweiterung des Minimalen Supersymmetrischen Standardmodells MSSM mit einem Singlett-Superfeld, so dass der Higgs-Sektor insgesamt sieben physikalische Higgs-Teilchen enth{\"a}lt, und zwar drei neutrale skalare, zwei pseudoskalare und zwei geladene. Weiterhin enth{\"a}lt das NMSSM f{\"u}nf Neutralinos gegen{\"u}ber vier im MSSM. In dieser Arbeit pr{\"a}sentieren wir die 5 x 5 Neutralinomischungsmatrix, stellen die Eigenwertgleichung auf und analysieren das Massenspektrum und die Parameterabh{\"a}ngigkeit m{\"o}glicher masseloser Zust{\"a}nde. F{\"u}r die Untersuchung von Neutralinoproduktion und -zerfall wurden verschiedene Szenarien gew{\"a}hlt, in denen das leichteste Neutralino eine Masse von 10 GeV und eine Singlettkomponente von {\"u}ber 90\% besitzt oder in denen das leichteste Neutralino bis zu 50 Gev schwer ist und sich der Singlettanteil auf die beiden leichtesten Neutralinos verteilt. Die Wirkungsquerschnitte f{\"u}r die Neutralinoproduktion wurden in den gew{\"a}hlten Szenarien f{\"u}r Schwerpunktsenergien von 100 GeV bis 600 GeV berechnet, also bis zu einem Bereich, den ein geplanter Elektron-Positron-Linearbeschleuniger erreichen kann. Typische Wirkungsquerschnitte f{\"u}r die direkte Produktion vorwiegend singlettartiger Neutralinos liegen im Bereich von 100 fb. Selbst wenn das leichteste Neutralino sehr leicht ist, kann das n{\"a}chste bereits so schwer sein, dass bei LEP2 nur die nicht nachtweisbare Paarproduktion des leichtesten supersymmetrischen Teilchens m{\"o}glich ist. Somit ist bei LEP2 keine Erh{\"o}hung der unteren Neutralinomassengrenzen im NMSSM zu erwarten, falls kein Neutralino gefunden wird. In Szenarien mit leichten singlettartigen Neutralinos k{\"o}nnen sehr oft auch sehr leichte Higgs-Bosonen mit Massen unterhalb der im MSSM vorhandenen Grenzen existieren. Somit kann in allen unseren Szenarien der Neutralinozerfall in ein skalares oder pseudoskalares Higgs-Boson m{\"o}glich sein und dann Verweigungsverh{\"a}ltnisse bis zu fast 100\% erreichen. Wir berechnen in dieser Arbeit f{\"u}r die bei LEP2 produzierbaren Neutralinos die Verwzeigungsverh{\"a}ltnisse f{\"u}r die Zweik{\"o}rperzerf{\"a}lle in Higgs-Bosonen, die Dreik{\"o}rperzerf{\"a}lle in zwei Fermionen und den Schleifenzerfall in ein Photon. In allen F{\"a}llen befindet sich im Endzustand außerdem das unsichtbare leichteste Neutralino, dass sich experimentell als fehlende Energie niederschl{\"a}gt. Zur Bestimmung der Signaturen betrachten wir außerdem die anschließenden Zerfallsmodi der leichten Higgs-Bosonen. Der Nachweis von leichten singlettartigen Neutralinos im NMSSM kann einerseits unm{\"o}glich sein, wenn entweder die schweren Neutralinos bei der verf{\"u}gbaren Schwerpunktsenergie nicht produziert werden k{\"o}nnen oder {\"u}ber Higgs-Bosonen vollkommen in das LSP zerfallen, andererseits aber auch durch klare Signaturen mit einem Photon oder mit Jets im Endzustand erleichtert werden. Bei LEP2 sollten also durchaus Chancen bestehen, auch im Rahmen des NMSSM ein Neutralino zu entdecken. Zumindest werden sich weitere Einschr{\"a}nkungen des Parameterraums ergeben. Der Dissertation ist ein Anhang beigef{\"u}gt, der eine vollst{\"a}ndige Liste aller Feynman-Regeln des NMSSM enth{\"a}lt, die sich von denjenigen des MSSM unterscheiden.},
  subject      = {Supersymmetrie},
  language  = {de}
}
@phdthesis{Deppisch2004,
  author    = {Deppisch, Frank},
  title     = {Towards a reconstruction of the SUSY seesaw model},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-12757},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {In this work, we studied in great detail how the unknown parameters of the SUSY seesaw model can be determined from measurements of observables at or below collider energies, namely rare flavor violating decays of leptons, slepton pair production processes at linear colliders and slepton mass differences. This is a challenging task as there is an intricate dependence of the observables on the unknown seesaw, light neutrino and mSUGRA parameters. In order to separate these different influences, we first considered two classes of seesaw models, namely quasi-degenerate and strongly hierarchical right-handed neutrinos. As a generalisation, we presented a method that can be used to reconstruct the high energy seesaw parameters, among them the heavy right-handed neutrino masses, from low energy observables alone.},
  subject      = {Supersymmetrie},
  language  = {en}
}
@phdthesis{Kittel2004,
  author    = {Kittel, Olaf},
  title     = {CP violation in production and decay of supersymmetric particles},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-12767},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {In dieser Dissertation untersuchen wir CP verletzende Effekte von MSSM-Phasen in Produktion und Zwei-Teilchen-Zerfaellen von Neutralinos, Charginos und Sfermionen. Fuer verschiedene supersymmetrische Prozesse definieren und berechnen wir CP-ungerade Asymmetrien, welche auf Spatprodukten basieren. Wir zeigen numerische Ergebnisse fuer Elektron-Positron-Kollisionen an einem zukuenftigen Linearbeschleuniger mit einer Energie von 500 - 800 GeV, hoher Luminositaet und longitudinal polarisierten Strahlen.},
  subject      = {Supersymmetrisches Teilchen},
  language  = {en}
}
@phdthesis{Redelbach2004,
  author    = {Redelbach, Andreas},
  title     = {SUSY Seesaw model and phenomenological implications for leptonic processes at low energies and leptogenesis},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-10182},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {In this work the supersymmetric seesaw model and its effects on low-energy leptonic observables and thermal leptogenesis have been systematically investigated. Precision measurements will increase the sensitivity on lepton-flavor violating decays, particularly on Br(l_j->l_i gamma) and also on electric and magnetic dipole moments in the near future. In order to improve also the accuracy of theoretical predictions for these processes, we have performed a full one-loop calculation of the underlying supersymmetric processes taking into account the lepton masses. Since the mechanism of soft supersymmetry breaking (SSB) is completely unknown, a novel analysis beyond the often studied minimal Supergravity scenarios has been performed. This way it has been demonstrated that in the considered mSUGRA, AMSB, GMSB and gaugino mediated scenarios, the ongoing search for Br(mu->e gamma) can constrain fundamental SSB parameters and/or the seesaw parameters. On the other hand, the basic parameters of thermal leptogenesis, such as the CP asymmetry in the decays of the lightest right-handed Majorana neutrino, provide probes of the unknown complex orthogonal R-matrix of the seesaw model.},
  subject      = {Supersymmetrie},
  language  = {en}
}
@phdthesis{Pahlen2005,
  author    = {Pahlen, Federico von der},
  title     = {Polarization and Spin Effects in Production and Decay of Charginos and Neutralinos at a Muon Collider},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-18421},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2005},
  abstract  = {The mechanism of spontaneous symmetry breaking is essential to provide masses to the W and Z gauge bosons and fermions of the SM. We hope to elucidate this mechanism at the next generation of colliders. While the SM has been tested with astonishing precision it is believed to be an effective theory of a more fundamental Great Unified Theory. SUSY is one of the most attractive extensions of the SM of particle physics. Therefore, the search for SUSY is a top priority at the next generation of colliders. Once Higgs bosons are discovered, a precise determination of their properties is necessary to differentiate between different models, in particular the MSSM. A muon collider, running at center of mass energies around the neutral Higgs boson resonances, would allow precise measurements of masses and widths, as well as the couplings to their decay products. In particular their couplings to supersymmetric particles are essential to probe SUSY. Therefore, we study the decays of the heavier CP-even and CP-odd Higgs bosons into lighter chargino or neutralino pairs. In this thesis we have analyzed the polarization effects of the beams and the charginos and neutralinos produced in mu+ mu- annihilation around the center of mass energies of the Higgs boson resonances H and A. For the production of equal charginos we have shown that the ratio of H-chargino and A-chargino couplings can be precisely determined independently of the chargino decay mechanism. This method avoids reference to other experiments and makes only a few model-dependent assumptions. Here we have analyzed the effect of the energy spread and of the error from the non-resonant channels, including an irreducible standard model background contribution. For small tan(beta) the process yields large cross sections of up to a pb. For the production of two different charginos we have shown that the H-A interference can be analyzed using asymmetries of the charge conjugated processes. The asymmetries depend on the muon longitudinal beam polarizations and vanish for unpolarized beams. For the chargino pair production with subsequent two-body decay of one of the charginos we have shown that charge and beam polarization asymmetries in the energy distributions of the decay particles are sensitive to the interference of scalar exchange channels with different CP quantum numbers. This process provides unique information on the interference of overlapping Higgs boson resonances. The effect is larger for regions of parameter space with intermediate values of tan(beta) and light sleptons or LSP neutralinos. For the chargino pair production with subsequent two-body decays of both charginos we have defined energy distribution and angular asymmetries in the final particles, in order to analyze the spin-spin correlations of the charginos. The transverse polarizations of the charginos are sensitive to the CP quantum number of the exchanged Higgs bosons and can thus be used to separate overlapping resonances, as well as to determine the CP quantum number of a single resonance. For equal charginos, these asymmetries are not sensitive to the interference of CP-even and CP-odd Higgs exchange channels. For the neutralino pair production in mu+ mu- annihilation we study similar processes as for chargino production. Line shape measurements of neutralino pair production allow to precisely determine the ratio of H-neutralino and A-neutralino couplings. Neutralino pair production with subsequent two-body decay of one of the neutralinos in the intermediate tan(beta) region is sensitive to the interference of H and A and may be measured with a large statistical significance. The Majorana nature of the neutralinos implies that the beam polarization asymmetries vanish for the remaining production channels. For neutralino pair production with subsequent two-body decays of both neutralinos we analyze similar observables as in chargino production. The main difference consists in the intrinsic relative CP quantum number of the neutralino pair, which depends on the chosen scenario. We have thus shown that the interaction of the Higgs bosons to the gaugino-higgsino sector can be probed at a muon collider in chargino and neutralino pair production, both analyzing the production line-shape around the resonances as well as studying the chargino and neutralino polarizations via their decays.},
  subject      = {Neutralino},
  language  = {en}
}
@phdthesis{Csallner2006,
  author    = {Csallner, Sigrun},
  title     = {Produktion und Nachweis schwerer Selektronen},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-22433},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2006},
  abstract  = {Wir studieren die Produktion und den Nachweis von Selektronen mit Massen jenseits der Schwelle zur Paarerzeugung an k{\"u}nftigen Linearbeschleunigern mit Schwerpunktsenergien von 500 GeV und 800 GeV. Hierzu betrachten wir die Produktion von linken und rechten Selektronen in Assoziation mit dem jeweils leichtesten Neutralino oder Chargino durch Elektron-Elektron-, Elektron-Positron- und Elektron-Photon-Streuung im Rahmen des MSSM. Die Produktion durch Elektron-Elektron-Streuung untersuchen wir zus{\"a}tzlich in zwei erweiterten Modellen, dem NMSSM und einem E6-Modell mit einem zus{\"a}tzlichen U(1)-Eichfaktor.},
  subject      = {Linearbeschleuniger},
  language  = {de}
}
@phdthesis{Wagner2008,
  author    = {Wagner, Alexander},
  title     = {Production of Sleptons in e¯e¯-Collisions},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-28307},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2008},
  abstract  = {Supersymmetry is currently the best motivated extension of the Standard Model and will be subject to extensive studies in the upcoming generation of colliders. The e-e- mode would be a straight forward extension to the currently planed International Linear Collider, planned to operate in e+e- mode. The low background in this mode may prove advantageous in the study of CP- and Lepton Flavour Violtation. In this work a CP sensitive observable based on transverse beam polarisation is introduced and the impact of neutralino mixing on the total cross section in cas of non-vanishing CP-violtating phases is studied in representative scenarios including non-GUT scenarios. Additionally, the mixing of sleptons is studied in the context of LFV, an analytical approximation is developed, and possible background free measurements of these effects are investigated.},
  subject      = {Supersymmetrie},
  language  = {en}
}
@phdthesis{Knochel2009,
  author    = {Knochel, Alexander Karl},
  title     = {Supersymmetry in a Sector of Higgsless Electroweak Symmetry Breaking},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-47899},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2009},
  abstract  = {Seit der Popularisierung durch Randall/Sundrum (RS) vor etwa 10 Jahren, und insbesondere in Verbindung mit der \$AdS/CFT\$-Korrespondenz, ist der Einsatz von gekr{\"u}mmten Raumzeithintergr{\"u}nden mit Extradimensionen (insb. des \$AdS_5\$) eine der fruchtbarsten neuen Ideen bei der Suche nach Modellen jenseits des Standardmodells (SM). Dieser Ansatz brachte nicht nur frische Einsichten in die Physik stark wechselwirkender Feldtheorien, die zuvor st{\"o}rungstheoretischen Methoden verschlossen waren, sondern schaffte auch einen faszinierenden neuen Zusammenhang zwischen ph{\"a}nomenologi-schen Modellen an der TeV-Skala und der Gravitation. Dies hat unter anderem auch das Interesse an Modellen der elektroschwachen Symmetriebrechung ohne physikalische Skalarfelder (Higgslose Modelle'') in diesem Kontext mit dem Ziel neu aufleben lassen, Alternativen zu dem im Standardmodell der Teilchenphysik enthaltenen Higgs-Mechanismus zu finden. Bei der Umsetzung dieser Ideen lag das Hauptaugenmerk meisst auf potentiellen neuen Betr{\"a}gen zu elektroschwachen Pr{\"a}zisionsobservablen. Gleichzeitig gibt es jedoch sehr starke astrophysikalische Indizien daf{\"u}r dass die Antwort auf die Frage nach dem Ursprung der beobachteten Dunkelmaterie in Teilchenmodellen jenseits des Standardmodells zu finden ist. Die Natur der elektroschwachen Symmetriebrechung und der Dunkelmaterie geh{\"o}ren zu den zentralen Fragen deren Beantwortung dank aktueller und anstehender Experimente z.B. an Beschleunigern wie dem Tevatron wie auch in naher Zukunft am LHC in greifbare N{\"a}he r{\"u}ckt. Diese Situation legt nahe dass neue Szenarien jenseits des Standardmodells beide Fragestellungen gleicherma\ss en thematisieren sollten. In der vorliegenden Arbeit untersuchen wir die ph{\"a}nomenologischen Implikationen einer Erweiterung Higgsloser Modelle in 5D um Supersymmetrie mit erhaltener R-Parit{\"a}t im elektroschwachen Symmetriebrechungssektor. Das Ziel war, eine m{\"o}glichst einfache Erweiterung zu finden, die ein realistisches leichtes Spektrum aufweist und gleichzeitig einen guten Kandidaten f{\"u}r kalte Dunkelmaterie enth{\"a}lt, ohne zu viele freie Parameter einzuf{\"u}hren. Um dies zu bewerkstelligen, bot sich der gleiche Mechanismus an, der bereits f{\"u}r die Brechung der Eichsymmetrien zum Einsatz kommt, n{\"a}mlich die Brechung durch Randbedingungen. W{\"a}hrend Supersymmetrie in 5D vier Superladungen beinhaltet und somit eng mit \$\mathcal{N}=2\$ Supersymmetrie in 4D verwandt ist, wird allein durch den RS-Hintergrund die H{\"a}lfte der Symmetrien gebrochen, so dass nach der Kaluza-Klein-Reduktion lediglich eine erhaltene Supersymmetrie verbleibt. Davon ausgehend war das einfachste gangbare Szenario, die Brechung der verbleibenden Generatoren effektiv durch Randbedingungen auf der UV-Brane der RS-Raumzeit zu beschreiben. Obwohl hierdurch Teile des leichten SUSY-Spektrums, insb. die Superpartner der Fermionen, ausprojeziert werden, verbleibt die reichhaltige Ph{\"a}nomenologie von vollst{\"a}ndigen \$\mathcal{N}=2\$-Multiplets im Kaluza-Klein-Sektor. Das leichte erweiterte Spektrum besteht aus den Superpartnern der elektroschwachen Eichbosonen, die Massen um \$\mathcal{O}(100\mbox{ GeV})\$ erhalten. Die Neutralinos als Masseneigenzust{\"a}nde des neutralen Bino-Wino-Sektors sind automatisch die leichtesten Supersymmetrischen Teilchen (LSP) und damit nat{\"u}rliche Kandidaten f{\"u}r kalte Dunkelmaterie. Ihre Reliktdichte kann ohne exzessive Feineinstellung von Parametern in Einklang mit Beobachtungen gebracht werden. Das Modell sagt somit eine leichte NLSP-Masse im Bereich \$m_{\chi^+}\approx 100\dots 110\$ GeV und einen LSP bei etwa \$m_\chi\approx 90\$ GeV voraus. Am LHC hat der nicht-supersymmetrische Teilcheninhalt des Modells weitestgehend die gleichen ph{\"a}nomenologischen Konsequenzen wie sie bereits von Studien Higgsloser Modelle bekannt sind. Wir haben uns daher auf die Produktion des LSP und NLSP am LHC als typische Signatur des erweiterten Modells konzentriert, und insbesondere Monte-Carlo-Simulationen mit \nameomega/\namewhizard~zur Beobachtung von fehlender transversaler Energie (\$\ptmiss\$) in Assoziation mit schweren Quarks durchgef{\"u}hrt. Wir diskutieren geeignete Schnitte auf Winkel, invariante Massen und Impulse, und erhalten Hadronische Produktionsquerschnitte von \$\sigma>100\mbox{ fb}\$ bei \$14\mbox{ TeV}\$, die charakteristische \$\ptmiss\$-Verteilungen im \$\chi\chi t\overline{t}\$ Endzustand aufweisen. Der Nachweis {\"u}ber die Produktion von \$b\$-Paaren erweist sich als schwieriger. Unsere Ergebnisse legen nahe dass die Entdeckung dieses Typs von Dunkelmaterie in Higgslosen Modellen am LHC {\"u}ber fehlende transversale Energie mit wenigen fb\$^{-1}\$ bei 14 TeV m{\"o}glich ist, insofern eine zuverl{\"a}ssige Identifikation schwerer Quarks gegeben ist.},
  subject      = {Supersymmetrie},
  language  = {en}
}
@phdthesis{Staub2010,
  author    = {Staub, Florian},
  title     = {Considerations on supersymmetric Dark Matter beyond the MSSM},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-55343},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2010},
  abstract  = {The standard model (SM) of particle physics is for the last three decades a very successful description of the properties and interactions of all known elementary particles. Currently, it is again probed with the first collisions at the Large Hadron Collider (LHC). It is widely expected that new physics will be detected at the LHC and the SM has to be extended. The most exhaustive analyzed extension of the SM is supersymmetry (SUSY). SUSY can not only solve intrinsic problems of the SM like the hierarchy problem, but it also postulates new particles which might explain the nature of dark matter in the universe. The majority of all studies about dark matter in the framework of SUSY has focused on the minimal supersymmetric standard model (MSSM). The aim of this work is to consider scenarios beyond that scope. We consider two models which explain not only dark matter but also neutrino masses: the gravitino as dark matter in gauge mediated SUSY breaking (GMSB) with bilinear broken \$R\$-parity as well as different seesaw scenarios with the neutralino as dark matter candidate. Furthermore, we also study the next-to-minimal supersymmetric standard model (NMSSM) which solves the \(\mu\)-problem of the MSSM and discuss the properties of the neutralino as dark matter candidate. In case of \$R\$-parity violation, light gravitinos are often the only remaining candidate for dark matter in SUSY because of their very long life time. We reconsider the cosmological gravitino problem arising for this kind of models. It will be shown that the proposed solution for the overclosure of the universe by light gravitinos, namely the entropy production by decays of GMSB messenger, just works in a small subset of models and in fine-tuned regions of the parameter space. This is a consequence of two effects so far overlooked: the enhanced decay channels in massive vector bosons and the impact of charged messenger particles. Both aspects cause an interplay between different cosmological restrictions which lead to strong constraints on the parameters of GMSB models. Afterwards, a minimal supergravity (mSugra) scenario with additional chiral superfields at high energy scales is considered. These fields are arranged in complete \$SU(5)\$ multiplets in order to maintain gauge unification. The new fields generate a dimension 5 operator to explain neutrino data. Furthermore, they cause large differences in mass spectrum of MSSM fields because of the different evaluation of the renormalization group equations what changes also the properties of the lightest neutralino as dark matter candidate. We discuss the parameter space of all three possible seesaw scenarios with respect to dark matter and the impact on rare lepton flavor violating processes. As we will see, especially in seesaw type~III but also in type~II the mass spectrum and regions of parameter space consistent with dark matter differ significantly in comparison to a common mSugra scenario. Moreover, the experimental bounds, in particular of branching ratios like \(l_i \rightarrow l_j \gamma\), cause large constraints on the seesaw parameters.},
  subject      = {Supersymmetrie},
  language  = {en}
}
@phdthesis{Liebler2011,
  author    = {Liebler, Stefan},
  title     = {LHC phenomenology and higher order electroweak corrections in supersymmetric models with and without R-parity},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69367},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2011},
  abstract  = {During the last decades the standard model of particle physics has evolved to one of the most precise theories in physics, describing the properties and interactions of fundamental particles in various experiments with a high accuracy. However it lacks on some shortcomings from experimental as well as from theoretical point of view: There is no approved mechanism for the generation of masses of the fundamental particles, in particular also not for the light, but massive neutrinos. In addition the standard model does not provide an explanation for the observance of dark matter in the universe. Moreover the gauge couplings of the three forces in the standard model do not unify, implying that a fundamental theory combining all forces can not be formulated. Within this thesis we address supersymmetric models as answers to these various questions, but instead of focusing on the most simple supersymmetrization of the standard model, we consider basic extensions, namely the next-to-minimal supersymmetric standard model (NMSSM), which contains an additional singlet field, and R-parity violating models. R-parity is a discrete symmetry introduced to guarantee the stability of the proton. Using lepton number violating terms in the context of bilinear R-parity violation and the munuSSM we are able to explain neutrino physics intrinsically supersymmetric, since those terms induce a mixing between the neutralinos and the neutrinos. Since 2009 the Large Hadron Collider (LHC) at CERN explores the new energy regime of Tera-electronvolt, allowing the production of potentially existing heavy particles by the collision of protons. Thus the near future might provide answers to the open questions of mass generation in the standard model and show hints towards physics beyond the standard model. Therefore this thesis works out the phenomenology of the supersymmetric models under consideration and tries to point out differences to the well-known features of the simplest supersymmetric realization of the standard model. In case of the R-parity violating models the decays of the light neutralinos can result in displaced vertices. In combination with a light singlet state these displaced vertices might offer a rich phenomenology like non-standard Higgs decays into a pair of singlinos decaying with displaced vertices. Within this thesis we present some calculations at next order of perturbation theory, since one-loop corrections provide possibly large contributions to the tree-level masses and decay widths. We are using an on-shell renormalization scheme to calculate the masses of neutralinos and charginos including the neutrinos and leptons in case of the R-parity violating models at one-loop level. The discussion shows the similarities and differences to existing calculations in another renormalization scheme, namely the DRbar scheme. Moreover we consider two-body decays of the form chi_j^0 -> chi_l^\pm W^\mp involving a heavy gauge boson in the final state at one-loop level. Corrections are found to be large in case of small or vanishing tree-level decay widths and also for the R-parity violating decay of the lightest neutralino chi_1^0 -> l^\pm W^\mp. An interesting feature of the models based on bilinear R-parity violation is the correlation between the branching ratios of the lightest neutralino decays and the neutrino mixing angles. We discuss these relations at tree-level and for two-body decays chi_1^0 -> l^\pm W^\mp also at one-loop level, since only the full one-loop corrections result in the tree-level expected behavior. The appendix describes the two programs MaCoR and CNNDecays being developed for the analysis carried out in this thesis. MaCoR allows for the calculation of mass matrices and couplings in the models under consideration and CNNDecays is used for the one-loop calculations of neutralino and chargino mass matrices and the two-body decay widths.},
  subject      = {Supersymmetrie},
  language  = {en}
}
@phdthesis{Krauss2013,
  author    = {Krauß, Martin Bernhard},
  title     = {Testing Models with Higher Dimensional Effective Interactions at the LHC and Dark Matter Experiments},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-94519},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2013},
  abstract  = {Dark matter and non-zero neutrino masses are possible hints for new physics beyond the Standard Model of particle physics. Such potential consequences of new physics can be described by effective field theories in a model independent way. It is possible that the dominant contribution to low-energy effects of new physics is generated by operators of dimension d>5, e.g., due to an additional symmetry. Since these are more suppressed than the usually discussed lower dimensional operators, they can lead to extremly weak interactions even if new physics appears at comparatively low scales. Thus neutrino mass models can be connected to TeV scale physics, for instance. The possible existence of TeV scale particles is interesting, since they can be potentially observed at collider experiments, such as the Large Hadron Collider. Hence, we first recapitulate the generation of neutrino masses by higher dimensional effective operators in a supersymmetric framework. In addition, we discuss processes that can be used to test these models at the Large Hadron Collider. The introduction of new particles can affect the running of gauge couplings. Hence, we study the compatibilty of these models with Grand Unified Theories. The required extension of these models can imply the existence of new heavy quarks, which requires the consideration of cosmological constraints. Finally, higher dimensional effective operators can not only generate small neutrino masses. They also can be used to discuss the interactions relevant for dark matter detection experiments. Thus we apply the methods established for the study of neutrino mass models to the systematic discussion of higher dimensional effective operators generating dark matter interactions.},
  subject      = {Neutrino},
  language  = {en}
}
@phdthesis{Krauss2015,
  author    = {Krauß, Manuel Ernst},
  title     = {Non-minimal supersymmetric models: LHC phenomenology and model discrimination},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-123555},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2015},
  abstract  = {It is generally agreed upon the fact that the Standard Model of particle physics can only be viewed as an effective theory that needs to be extended as it leaves some essential questions unanswered. The exact realization of the necessary extension is subject to discussion. Supersymmetry is among the most promising approaches to physics beyond the Standard Model as it can simultaneously solve the hierarchy problem and provide an explanation for the dark matter abundance in the universe. Despite further virtues like gauge coupling unification and radiative electroweak symmetry breaking, minimal supersymmetric models cannot be the ultimate answer to the open questions of the Standard Model as they still do not incorporate neutrino masses and are besides heavily constrained by LHC data. This does, however, not derogate the beauty of the concept of supersymmetry. It is therefore time to explore non-minimal supersymmetric models which are able to close these gaps, review their consistency, test them against experimental data and provide prospects for future experiments. The goal of this thesis is to contribute to this process by exploring an extraordinarily well motivated class of models which bases upon a left-right symmetric gauge group. While relaxing the tension with LHC data, those models automatically include the ingredients for neutrino masses. We start with a left-right supersymmetric model at the TeV scale in which scalar \(SU(2)_R\) triplets are responsible for the breaking of left-right symmetry as well as for the generation of neutrino masses. Although a tachyonic doubly-charged scalar is present at tree-level in this kind of models, we show by performing the first complete one-loop evaluation that it gains a real mass at the loop level. The constraints on the predicted additional charged gauge bosons are then evaluated using LHC data, and we find that we can explain small excesses in the data of which the current LHC run will reveal if they are actual new physics signals or just background fluctuations. In a careful evaluation of the loop-corrected scalar potential we then identify parameter regions in which the vacuum with the phenomenologically correct symmetry-breaking properties is stable. Conveniently, those regions favour low left-right symmetry breaking scales which are accessible at the LHC. In a slightly modified version of this model where a \(U(1)_R × U(1)_{B-L}\) gauge symmetry survives down to the TeV scale, we implement a minimal gauge-mediated supersymmetry breaking mechanism for which we calculate the boundary conditions in the presence of gauge kinetic mixing. We show how the presence of the extended gauge group raises the tree-level Higgs mass considerably so that the need for heavy supersymmetric spectra is relaxed. Taking the constraints from the Higgs sector into account, we then explore the LHC phenomenology of this model and point out where the expected collider signatures can be distinguished from standard scenarios. In particular if neutrino masses are explained by low-scale seesaw mechanisms as is done throughout this work, there are potentially spectacular signals at low-energy experiments which search for charged lepton flavour violation. The last part of this thesis is dedicated to the detailed exploration of processes like μ → e γ, μ → 3 e or μ-e conversion in nuclei in a supersymmetric framework with an inverse seesaw mechanism. In particular, we disprove claims about a non-decoupling effect in Z-mediated three-body decays and study the prospects for discovering and distinguishing signals at near-future experiments. In this context we identify the possibility to deduce from ratios like BR(\(τ → 3 μ\))/BR(\(τ → μ e^+ e^-\)) whether the contributions from ν - W loops dominate over supersymmetric contributions or vice versa.},
  subject      = {Supersymmetrie},
  language  = {en}
}
@phdthesis{Schreyer2015,
  author    = {Schreyer, Manuel},
  title     = {Search for supersymmetry in events containing light leptons, jets and missing transverse momentum in \(\sqrt{s}\) = 8 TeV pp collisions with the ATLAS detector},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-120863},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2015},
  abstract  = {The results of two analyses searching for supersymmetry (SUSY) in data of the ATLAS experiment are presented in this thesis. The data were recorded in proton-proton collisions at the Large Hadron Collider in 2012 at a centre of mass energy of \(\sqrt{s}\)=8 TeV and correspond to an integrated luminosity of 20.3 fb\(^{-1}\). The first search is performed in signatures containing an opposite-sign electron or muon pair, which is compatible with originating from a Z boson decay, in addition to jets and large missing transverse momentum. The analysis targets the production of squarks and gluinos in R-parity conserving (RPC) models with SUSY breaking via General Gauge Mediation (GGM). The main Standard Model (SM) backgrounds are \(t\overline t\), WW, W+t and Z to \(\tau \tau\) processes which are entirely estimated from data using different-flavour events. Besides that, the SM production of Z bosons in association with jets and large fake missing momentum from mismeasurements plays a role and is predicted with the data-driven jet smearing method. Backgrounds from events with fake leptons are estimated with the data-driven matrix method. WZ/ZZ production as well as smaller background contributions are determined from Monte-Carlo simulations. The search observes an excess of data over the SM prediction with a local significance of 3.0 \(\sigma\) in the electron channel, 1.7 \(\sigma\) in the muon channel and 3.0 \(\sigma\) when the two channels are added together. The results are used to constrain the parameters of the GGM model. The second analysis uses the already published results of an ATLAS search for SUSY in events with one isolated electron or muon, jets and missing transverse momentum to reinterpret them in the context of squark and gluino production in SUSY models with R-parity violating (RPV) \(LQ\overline D\)-operators. In contrast to RPC models, the lightest SUSY particle (LSP) is not stable but decays into SM particles. "Standard" analyses often do not consider SUSY models with RPV although they are in principle sensitive to them. The exclusion limits on the squark and gluino mass obtained from the reinterpretation extend up to 1200 GeV. These are the first results by any ATLAS SUSY search which systematically cover a wide range of RPV couplings in the case of prompt LSP decays. However, the analysis is not sensitive to the full parameter space of the \(LQ\overline D\)-model and reveals gaps in the ATLAS SUSY program which have to be closed by dedicated search strategies in the future.},
  subject      = {Supersymmetrie},
  language  = {en}
}