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This article deals with the bibliometric approach to the metadata of a dissertation record in a catalogue or database. As a document, a dissertation provides data on new knowledge, but also encodes important scientometric information. Research advising is one of main scholarly communication formal links (besides co-authorship and citation) in a social structure of science. PhD records may expose a scientific relation of research - advising both at the personal and institutional levels within a certain scientific area. This survey was inspired by bibliographical indexes of dissertation output in certain fields and during certain periods: 1793 to 1842, 1940 to 1993 in one country – Lithuania. The survey of selected scientific communities from 1945 to 1990 in Lithuania reveals a vast retrospective of scholarly communication, however, it is fragmented and not satisfactory for a comprehensive prosopographic mapping of scholarly communities within a science field or a country. After reviewing a tradition and style of electronic theses and dissertations (ETD) cataloguing and metadata creation, obstacles for prosopographic surveys and data mining in catalogues and databases of ETDs are revealed.

This thesis is concerned with the calculation of fixed moments of the $O(a_s^3)$ heavy flavor contributions to the Wilson coefficients of the structure function $F_2(x,Q^2)$ in the limit $Q^2 >> m^2$, neglecting power corrections. The massive Wilson coefficients in the asymptotic region are given as convolutions of massive operator matrix elements (OMEs) and the known light flavor Wilson coefficients. The former derive from the twist--2 operators emerging in the light--cone--expansion and are calculated at the 3--loop level for fixed moments. We also compute the massive OMEs which are needed to evaluate heavy flavor parton distributions in the variable flavor number scheme to the same order. All contributions to the Wilson coefficients and OMEs but the genuine constant terms at $O(a_s^3)$ of the OMEs are derived in terms of quantities, which are known for general values in the Mellin variable N. For the OMEs $A_{Qg}^(3)$, $A_{qg,Q}^(3)$ and $A_{gg,Q}^(3)$ the moments $N = 2$ to 10, for $A_{Qq}^{(3), PS}$ to $N = 12$, and for $A_{qq,Q}^{(3), NS}$, $A_{qq,Q}^{(3), PS}$, $A_{gq,Q}^(3)$to $N=14$ are computed. These terms contribute to the light flavor +-combinations. For the flavor non-singlet terms, we calculate as well the odd moments $N=1$ to 13, corresponding to the light flavor --combinations. We also obtain moments of the terms ~ $T_F$ of the 3-loop anomalous dimensions in an independent calculation, which agree with results given in the literature. The mathematical structure of the occurring momentum integrals and of the final results in terms of harmonic sums is discussed. We study applications of the same techniques to the polarized and transversity case at the NLO and NNLO level as well.

Universität Hamburg, Diplomarbeit, 2010; 98 pp., (2010). doi:10.3204/DESY-THESIS-2010-021, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diplomarbeit, 2010; 82 pp., (2010). doi:10.3204/DESY-THESIS-2010-026, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2010; 124 pp., (2010). doi:10.3204/DESY-THESIS-2010-009, A search for gravitinos produced in supersymmetric events in electron proton collisions has been performed with data recorded with the ZEUS detector at HERA in the years 2003 to 2007. In R-parity violating supersymmetric models a neutralino can be produced by t-channel exchange of a selectron between the incoming electron and a quark of the proton. In the Gauge Mediated Supersymmetry Breaking model (GMSB), where the gravitino is the lightest supersymmetric particle, the neutralino in large regions of the parameter space dominantly decays into a gravitino and a photon, leading to events with an isolated high energetic photon and large missing transverse momentum. To separate signal and background, a multi-variate discriminant method was used. No evidence for supersymmetry was found, and limits were derived for the R-parity violating coupling strength and the masses of the selectron and the lightest neutralino. Moreover, the cluster position reconstruction system of the ZEUS experiment was improved by modifying and implementing an algorithm which uses estimated track angle and impact position from the pattern recognition phase of the tracking system to yield a better position resolution., Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2009; 174 pp., (2009). doi:10.3204/DESY-THESIS-2009-017, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2008; 194 pp., (2008). doi:10.3204/DESY-THESIS-2008-002, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2007; 108 pp., (2007). doi:10.3204/DESY-THESIS-2007-009, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2007; 157 pp. (2007). = Universität Hamburg, Diss., 2007, We study Gauge-Higgs unification model on the orbifold $S^{1}/Z_{2}$ based on the extended SM gauge group $G_{SM}^{ex}=SU(2)_{L} \times U(1)_{Y} \times SO(3)_{F}$. The group $SO(3)_{F}$ is treated as a chiral gauged flavour symmetry. Electroweak-, flavour- and Higgs interactions are unified in one single gauge group SU(7) which is broken again down to $G_{SM}^{ex}$ by orbifolding and imposing additional boundary conditions. The compactification scale is O(1) TeV. The orbifold $S^{1}/Z_{2}$ is put on a lattice. This setting gives a staring point for RG-transformations. As a result the bulk is integrated out and the extra dimension consist of only two points: the orbifold fixed points. Parallel transporters (PT) in the extra dimension become nonunitary as a result of the blockspin transformations. In addition, a Higgs potential emerges naturally. The PTs can be written as a product $e^{A_{y}} e^{\eta} e^{A_{y}}$ of unitary factors $e^{A_{y}}$ and a selfadjoint factor $e^{\eta}$. The reduction $48 \to 35 + 6 + \bar{6} + 1$ of the adjoint reps of SU(7) with respect to $SU(6) \supset G_{SM}^{ex}$ leads to three $SU(2)_{L}$ Higgs doublets: one for each flavour. Their zero modes serve as a substitute for the SM Higgs. When $G_{SM}^{ex}$ is spontaneously broken down to $U(1)_{em}$, an exponential gauge boson mass splitting occurs naturally. This breaking leads to $SO(3)_{F}$ flavour gauge boson masses much above the compactification scale. Thus tree-level FCNC are naturally suppressed. Making some simplifying assumptions we also calculate fermion masses and CKM mixing angles. As for the gauge bosons an exponential fermion mass splitting occurs naturally. The model predicts a large Higgs sector consisting of 30 Higgs particles and in its simplest form the weak mixing angle $\theta=0.125$.

Wir stellen eine Untersuchung einer Kombination zwischen HQET und relativistischer QCD vor, die das Ziel hat, die b-Quark Masse und die Zerfallskonstante des Bs-Mesons aus Gitter-Simulationen, unter Nichtbeachtung virtueller Fermionenschleifen, zu gewinnen. Wir beginnen mit einem kleinen Volumen, in dem man das b-Quark direkt simulieren kann, und stellen die numerische Verbindung mit einem großen Volumen, wo ``finite-size'''' Effekte vernachlässigbar sind, mit Hilfe einer ``finite-size'''' Methode her. Diese besteht aus zum Kontinuum extrapolierten Schritten, wobei der Massenpunkt, der der physikalischen b-Quark Masse entspricht, durch eine Interpolation erreicht wird. In diese Interpolation fliessen die in der HQET erzielten Resultate ein. Mit dem durch die Sommersche Skale r0 bestimmten Gitterabstand und den experimentalen Werten für die Bs- und K-Massen erhalten wir die Endergebnisse für die renormierungsgruppeninvariante Masse Mb = 6.88(10) GeV, äquivalent zu mb(mb) = 4.42(6) GeV in dem MSbar-Schema und fBs = 191(6) MeV für die Zerfallskonstante. Eine Renormierungsbedingung für den Chromo-magnetischen Operator, der in führender Ordnung der Entwicklung in der schweren Quarkmasse in HQET für die Massenaufspaltung zwischen dem pseudoskalaren und dem vektoriellen Kanal mesonischer schwer-leicht gebundener Zustände verantwortlich ist, wird auf der Basis von Gitter-Korrelationsfunktionen bereitgestellt. Dies eignet sich gut für eine nicht-störungstheoretische Rechnung, welche einen großen Bereich der Renormierungsskala umfasst und keine Valenz-Quarks beinhaltet. Die Zwei-Schleifen Ordnung der entsprechenden anomalen Dimension im Schrödinger-Funktional-Schema wird mit Hilfe von veröffentlichten Ergebnissen berechnet; dies erforderte eine neue Ein-Schleifen Rechnung im SF-Schema mit einem nicht verschwindenden Hintergrundfeld. Die Gitterartefakte bezüglich der Skalenentwicklung des Renormierungsfaktors werden zur Ein-Schleifen Ordnung untersucht, und es wird von nicht-störungstheoretischen Simulationen, unter Nichtbeachtung virtueller Fermionenschleifen, bestätigt, dass sie für die gegenwärtige verfügbare numerische Präzision vernachlässigbar sind., We present a study of a combination of HQET and relativistic QCD to extract the b-quark mass and the Bs-meson decay constant from lattice quenched simulations. We start from a small volume, where one can directly simulate the b-quark, and compute the connection to a large volume, where finite size effects are negligible, through a finite size technique. The latter consists of steps extrapolated to the continuum limit, where the b-region is reached through interpolations guided by the effective theory. With the lattice spacing given in terms of the Sommer''s scale r0 and the experimental Bs and K masses, we get the final results for the renormalization group invariant mass Mb = 6.88(10) GeV, translating into mb(mb) = 4.42(6) GeV in the MSbar scheme, and fBs = 191(6) MeV for the decay constant. A renormalization condition for the chromo-magnetic operator, responsible, at leading order in the heavy quark mass expansion of HQET, for the mass splitting between the pseudoscalar and the vector channel in mesonic heavy-light bound states, is provided in terms of lattice correlations functions which well suits a non-perturbative computation involving a large range of renormalization scales and no valence quarks. The two-loop expression of the corresponding anomalous dimension in the Schrödinger functional (SF) scheme is computed starting from results in the literature; it requires a one-loop calculation in the SF scheme with a non-vanishing background field. The cutoff effects affecting the scale evolution of the renormalization factors are studied at one-loop order, and confirmed by non-perturbative quenched computations to be negligible for the numerical precision achievable at present.

Universität Hamburg, Diss., 2007; 155 pp. (2007). = Universität Hamburg, Diss., 2007, Quantum gravity is analyzed from the viewpoint of the renormalization group. The analysis is based on methods introduced by J. Polchinski concerning the perturbative renormalization with flow equations. In the first part of this work, the program of renormalization with flow equations is reviewed and then extended to effective field theories that have a finite UV cutoff. This is done for a scalar field theory by imposing additional renormalization conditions for some of the nonrenormalizable couplings. It turns out that one so obtains a statement on the predictivity of the effective theory at scales far below the UV cutoff. In particular, nonrenormalizable theories can be treated without problems in the proposed framework. In the second part, the standard covariant BRS quantization program for Euclidean Einstein gravity is applied. A momentum cutoff regularization is imposed and the resulting violation of the Slavnov-Taylor identities is discussed. Deriving Polchinski's renormalization group equation for Euclidean quantum gravity, the predictivity of effective quantum gravity at scales far below the Planck scale is investigated with flow equations. A fine-tuning procedure for restoring the violated Slavnov-Taylor identities is proposed and it is argued that in the effective quantum gravity context, the restoration will only be accomplished with finite accuracy. Finally, the no-cutoff limit of Euclidean quantum gravity is analyzed from the viewpoint of the Polchinski method. It is speculated whether a limit with nonvanishing gravitational constant might exist where the latter would ultimatively be determined by the cosmological constant and the masses of the elementary particles.

Justus-Liebig-Universität Gießen, Diss., 2007; 135 pp., (2007). doi:10.3204/DESY-THESIS-2007-008, The HERMES experiment at DESY, Germany was designed to carry out precision measurements of the proton spin structure using polarised deep-inelastic leptonnucleon scattering. The experiment utilises the 27.5 GeV/c electron or positron beam of the HERA accelerator which is longitudinally polarised at HERMES, in combination with a longitudinal polarised internal gas target. The key to understanding the origins of the spin of the nucleon is widely believed to lie in a successful description of the interactions of the quarks and gluons from which it is formed. The internal structure of the nucleon is embodied in parton distributions of the constituent quarks and gluons. The spin-averaged parton distribution functions q(x) of quarks and antiquarks of flavours q = (u, d, s) describe the parton momentum distributions. The differences, or helicity distributions, q(x) = q''(x) − q'#(x), describe the flavour dependent contributions of the constituent partons to the spin of the nucleon. The helicity distribution of the strange quarks sea, S(x), is an essential feature of the spin structure of the nucleon. Its properties reflect the reaction mechanism that is responsible for the formation of the quark sea. Much of the information on nucleon spin structure, in particular, the observation that an unexpected small fraction of the spin of the proton comes from the intrinsic quark spins is based on an analysis of inclusive deeply inelastic scattering and hyperon decay under the assumption of SU(3) symmetry among the structures of the octet baryons. In these experiments (EMC and SMC), the helicity distribution for strange quarks were directly accessible to measurement. The strange quark sea was observed to have a substantial negative polarisation. The violation of the Ellis-Jaffe sum rule observed in that analysis was v vi Abstract attributed to this negative polarisation. To the extent that the virtual sea quarks are generated by gluon splitting, a non-zero strange quark polarisation can be attributed to a substantial polarisation of the gluons. Indeed, it has been speculated that the observed value of the strange sea helicity distribution results from a large positive gluon polarisation. In contrast to the earlier inclusive measurements, recent data from semi-inclusive DIS at HERMES suggest that the strange sea is unpolarised. A full 5 parameter flavour decomposition using data from proton and deuteron targets, although not sensitive to the anti-strange quark spin ¯s, yielded s = 0.028 ± 0.033 ± 0.009. A separate extraction of s+¯s from DIS data on the deuteron alone gave s+¯s = 0.129 ± 0.042 ± 0.129 where the large systematic error reflects the lack of knowledge of the kaon fragmentation functions. This thesis reports a new ”isoscalar” measurement of s + ¯s in which these limitations are avoided. Because strange quarks carry no isospin, the strange seas in the proton and neutron are identical. In the deuteron, an isoscalar target, the fragmentation process in DIS can be described without any assumptions regarding isospin dependent fragmentation. In the isoscalar extraction of s + ¯s only the spin asymmetry for K0 s AK0 s 1,d (x,Q2, z) and the inclusive asymmetry A1,d(x,Q2) are used. An accurate measurement of the total non-strange quark polarisation Q = u + ¯u + d + ¯ d comes directly from A1,d(x,Q2). The fragmentation functions needed for a leading order (LO) extraction of S = s + ¯s are measured directly at HERMES kinematics using the same data. As a result of this analysis, the helicity densities for the strange quarks are consistent with zero with the experimental uncertainty over the measured x kinematic range., Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2006; 143 pp. (2006). = Universität Hamburg, Diss., 2006, We study field theories on the noncommutative Minkowski space with noncommuting time. The focus lies on dispersion relations in quantized interacting models in the Yang-Feldman formalism. In particular, we compute the two-point correlation function of the field strength in noncommutative quantum electrodynamics to second order. At this, we take into account the covariant coordinates that allow the construction of local gauge invariant quantities (observables). It turns out that this does not remove the well-known severe infrared problem, as one might have hoped. Instead, things become worse, since nonlocal divergences appear. We also show that these cancel in a supersymmetric version of the theory if the covariant coordinates are adjusted accordingly. Furthermore, we study the phi^3 and the Wess-Zumino model and show that the distortion of the dispersion relations is moderate for parameters typical for the Higgs field. We also disuss the formulation of gauge theories on noncommutative spaces and study classical electrodynamics on the noncommutative Minkowski space using covariant coordinates. In particular, we compute the change of the speed of light due to nonlinear effects in the presence of a background field. Finally, we examine the so-called twist approach to quantum field theory on the noncommutative Minkowski space and point out some conceptual problems of this approach.

Universität Hamburg, Diss., 2006; 120 pp., (2006). doi:10.3204/DESY-THESIS-2006-015, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2006; 112 pp. (2006). = Universität Hamburg, Diss., 2006, In this thesis we investigate the effective actions for massive Kaluza-Klein states, focusing on the massive modes of spin-3/2 and spin-2 fields. To this end we determine the spontaneously broken gauge symmetries associated to these `higher spin' states and construct the unbroken phase of the Kaluza-Klein theory. We show that for the particular background AdS_3 x S*3 x S*3 a consistent coupling of the first massive spin-3/2 multiplet requires an enhancement of local supersymmetry, which in turn will be spontaneously broken in the Kaluza-Klein vacuum. The corresponding action is constructed as a gauged maximal supergravity in D=3. Subsequently, the symmetries underlying an infinite tower of massive spin-2 states are analyzed in case of a Kaluza-Klein compactification of four-dimensional gravity to D=3. It is shown that the resulting gravity-spin-2 theory is given by a Chern-Simons action of an affine algebra. The global symmetry is determined, which contains an affine extension of the Ehlers group. We show that the broken phase can in turn be constructed via gauging a certain subgroup of the global symmetry group. Finally, deformations of the Kaluza-Klein theory on AdS_3 x S*3 x S*3 and the corresponding symmetry breakings are analyzed as possible applications for the AdS/CFT correspondence.

Universität Hamburg, Diss., 2006; 91 pp., (2006). doi:10.3204/DESY-THESIS-2006-034, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2006; 112 pp., (2006). doi:10.3204/DESY-THESIS-2006-016, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Justus Liebig Universität Giessen, Diss., 2006; 110 pp., (2006). doi:10.3204/DESY-THESIS-2006-014, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

University of Glasgow, Diss., 2006; 195 pp., (2006). doi:10.3204/DESY-THESIS-2006-024, The HERMES experiment is a large forward angle spectrometer located at the HERA accelerator ring at DESY, Hamburg. This thesis presents the analysis of the kinematic dependencies of 0 vector meson production on hydrogen and deuterium targets. The relative gluon and quark contribution to the 0 production amplitude is expected to depend on the kinematical variable xBj , and by measuring the ratio of 0 electroproduction cross sections on deuterium and hydrogen from HERMES data this dependence is conrmed. This thesis describes the methods used to extract the cross section ratio from the HERMES data taken between the years 1996 and 2000 and compares the results with the theoretical predictions. Until 2005 the missing mass resolution of the HERMES spectrometer was only suf- cient to allow exclusivity at the level of a data sample. The HERMES Recoil Detector, installed in early 2006, is an upgrade which will augment the HERMES spectrometer by establishing exclusivity at the event level and therefore improving the resolution to which various kinematical variables may be reconstructed. Additionally, the Recoil Detector will contribute to the overall background suppression capability of the HERMES spectrometer. These improvements will provide a strong reduction in the statistical uncertainties present in the 0-analysis and other analyses at HERMES. The Recoil Detector critically relies on its track reconstruction software to enable its capability to provide event level exclusive measurements. This tracking code is presented in detail., Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2006; 136 pp. (2006). = Universität Hamburg, Diss., 2006, We present a Monte-Carlo event generator for simulating chargino pair production at the ILC at next-to-leading order in the electroweak couplings. We consider two approaches of including photon radiation. A strict fixed-order approach allows for comparison and consistency checks with published semianalytic results in the literature. A version with soft- and hard-collinear resummation of photon radiation, which combines photon resummation with the inclusion of the NLO matrix element for the production process, avoids negative event weights, so the program can simulate physical (unweighted) event samples. Photons are explicitly generated throughout the range where they can be experimentally resolved. In addition, it includes further higher-order corrections unaccounted for by the fixed-order method. Inspecting the dependence on the cutoffs separating the soft and collinear regions, we evaluate the systematic errors due to soft and collinear approximations for NLO and higher-order contributions. In the resummation approach, the residual uncertainty can be brought down to the per-mil level, coinciding with the expected statistical uncertainty at the ILC. We closely investigate the two-photon phase space for the resummation method. We present results for cross sections and event generation for both approaches.

Friedrich-Alexander-Universität Erlangen-Nürnberg, Diss., 2005; 303 pp., (2005). doi:10.3204/DESY-THESIS-2005-008, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2005; 177 pp., (2005). doi:10.3204/DESY-THESIS-2005-044, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Friedrich-Alexander-Universität Erlangen-Nürnberg, Diss., 2005; 158 pp., (2005). doi:10.3204/DESY-THESIS-2005-027, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

University of Ulm, Diplomarbeit, 2005; 104 pp., (2005). doi:10.3204/DESY-THESIS-2005-031, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2005; 134 pp., (2005). doi:10.3204/DESY-THESIS-2005-001, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2005; 187 pp., (2005). doi:10.3204/DESY-THESIS-2005-034, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2005; 140 pp. (2005). = Universität Hamburg, Diss., 2005, The subject of this thesis is the modular group of automorphisms acting on the massive algebra of local observables having their support in bounded open subsets of Minkowski space. After a compact introduction to micro-local analysis and the theory of one-parameter groups of automorphisms, which are used exensively throughout the investigation, we are concerned with modular theory and its consequences in mathematics, e.g., Connes cocycle theorem and classification of type III factors and Jones index theory, as well as in physics, e.g., the determination of local von Neumann algebras to be hyperfinite factors of type III_1, the formulation of thermodynamic equilibrium states for infinite-dimensional quantum systems (KMS states) and the discovery of modular action as geometric transformations. However, our main focus are its applications in physics, in particular the modular action as Lorentz boosts on the Rindler wedge, as dilations on the forward light cone and as conformal mappings on the double cone. Subsequently, their most important implications in local quantum physics are discussed. The purpose of this thesis is to shed more light on the transition from the known massless modular action to the wanted massive one in the case of double cones. First of all the infinitesimal generator of the massive modular group is investigated, especially some assumptions on its structure are verified explicitly for the first time for two concrete examples. Then, two strategies for the calculation of group itself are discussed. Some formalisms and results from operator theory and the method of second quantisation used in this thesis are made available in the appendix.

Universität Hamburg, Diss., 2005; 119 pp. (2005). = Universität Hamburg, Diss., 2005, We establish the existence of Bogoliubov's local scattering operators for P(\phi)_2 models of constructive quantum field theory in a nonperturbative way. To this end, we use the technique of evolution semigroups to prove a new result on wellposedness of the Cauchy problem for the time-dependent Schrodinger equation under very general assumptions.

Universität Hamburg, Diss., 2005; 194 pp., (2005). doi:10.3204/DESY-THESIS-2005-010, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

150 pp. (2005)., In absence of the Standard Model Higgs boson the interaction among the gauge bosons becomes strong at high energies ($\sim$ 1TeV) and influences the couplings between them. Each trilinear and quartic gauge boson vertex is characterized by a set of couplings which are expected to deviate from their Standard Model values already at energies lower than the energy scale of the New Physics. The precise measurement of gauge boson couplings can provide clues to the mechanism of the electroweak symmetry breaking and their anomalous values can be a sign of a New Physics effect beyond the Standard Model. Estimation of the precision with which we can measure the deviations of the charged trilinear gauge boson couplings (TGCs) with a photon collider at TESLA is one of the two topics covered by this theses. Deviations are denoted as $\Delta k_ \gamma$ and $\Delta \lambda_\gamma$ (anomalous TGCs) and represent the strength of the gauge boson couplings at the $WW_\gamma$, vertices. The single $W$ boson production in $\gamma e$ collisions is studied via $\gamma e^{-} \to W^{-}\nu_e$ in two different operating $\gamma e$ modes - real and parasitic. While the first assumes the electron and photon beam in the collision, the second one is considered as a background to $\gamma\gamma$ collisions: the interaction between photons (from each side) and unconverted electrons. The $W$ boson pair production is studied in $\gamma\gamma$ collisions via $\gamma\gamma \to W^+ W^-$ in two different initial polarization states, $J_z = 0$ and $|J_z| = 2$. While the first polarization state assumes the colliding photons have the same helicities, the second one assumes opposite photon helicities. The $W$ bosons from both channels are reconstructed from hadronic final states, as two jets in $\gamma e$ collisions and as four jets in $\gamma\gamma$ collisions. The study includes the influence of low-energy events $\gamma\gamma \to hadrons$ (pileup) on the signal and estimated background in both channels. The error estimation of the measurement of the TGCs is performed using a binned $X^2$ and binned maximum Likelihood fit of reweighted event distributions of variables which are sensitive to the anomalous couplings. It was found that the error of the $k_\gamma$, and $|lambda_\gamma$ measurement at a photon collider at TESLA is of $\mathcal 0(10^{-3} - 10{^-4})$, depending on the $\gamma\gamma/\gamma e$ channel, mode and the coupling under the consideration. Compared to the measurements at Tevatron and LEP experiments this is about one to two orders of magnitude higher accuracy. The influence of some systematic errors such those from the W mass measurement, uncertainties due to the beam energy and polarization and the effects of the background is also estimated. Another part of this theses covers the optimization of the $\gamma\gamma$-detector in the forward region. Detailed 'incoherent particle-particle' and 'coherent particle-beam' interactions have been simulated in order to estimate the low-energy background contribution to the tracking devices. The $\gamma\gamma$-detector is optimized in the way to minimize the direct and the backscattered background in its forward region. For that purpose, the beam pipes in the region between the interaction point and the electromagnetic calorimeter are surrounded by a tungsten mask. The space around the beam pipes in the region where the electromagnetic and hadronic calorimeters are positioned is filled by graphite and tungsten, while the outgoing electron beam pipes are made of graphite. With this design of the forward region the estimated background that enters into the main tracking system, the time projection chamber (TPC) and the vertex detector (VTX) is brought to the level that provides small occupancies in TPC and VTX.

Universität Hamburg, Diss., 2005; (2005). doi:10.1002/prop.200510252, In this review article we study type IIB superstring compactifications in the presence of space-time filling D-branes while preserving N=1 supersymmetry in the effective four-dimensional theory. This amount of unbroken supersymmetry and the requirement to fulfill the consistency conditions imposed by the space-time filling D-branes lead to Calabi-Yau orientifold compactifications. For a generic Calabi-Yau orientifold theory with space-time filling D3- or D7-branes we derive the low-energy spectrum. In a second step we compute the effective N=1 supergravity action which describes in the low-energy regime the massless open and closed string modes of the underlying type IIB Calabi-Yau orientifold string theory. These N=1 supergravity theories are analyzed and in particular spontaneous supersymmetry breaking induced by non-trivial background fluxes is studied. For D3-brane scenarios we compute soft-supersymmetry breaking terms resulting from bulk background fluxes whereas for D7-brane systems we investigate the structure of D- and F-terms originating from worldvolume D7-brane background fluxes. Finally we relate the geometric structure of D7-brane Calabi-Yau orientifold compactifications to N=1 special geometry., Published by Wiley-VCH, Berlin

Universität Hamburg, Diss., 2005; 101 pp., (2005). doi:10.3204/DESY-THESIS-2005-024, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Friedrich-Alexander-Universität Erlangen-Nürnberg, Diss., 2005; 177 pp., (2005). doi:10.3204/DESY-THESIS-2005-035, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2005; 125 pp., (2005). doi:10.3204/DESY-THESIS-2005-023, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2005; 144 pp., (2005). doi:10.3204/DESY-THESIS-2005-043, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg

Universität Hamburg, Diss., 2005; 132 pp. (2005). = Universität Hamburg, Diss., 2005, This article first reviews the calculation of the N = 1 effective action for generic type IIA and type IIB Calabi-Yau orientifolds in the presence of background fluxes by using a Kaluza-Klein reduction. The Kahler potential, the gauge kinetic functions and the flux-induced superpotential are determined in terms of geometrical data of the Calabi-Yau orientifold and the background fluxes. As a new result, it is shown that the chiral description directly relates to Hitchin's generalized geometry encoded by special odd and even forms on a threefold, whereas a dual formulation with several linear multiplets makes contact to the underlying N = 2 special geometry. In type IIB setups, the flux-potentials can be expressed in terms of superpotentials, D-terms and, generically, a massive linear multiplet. The type IIA superpotential depends on all geometric moduli of the theory. It is reviewed, how type IIA orientifolds arise as a special limit of M-theory compactified on specific G_2 manifolds by matching the effective actions. In a similar spirit type IIB orientifolds are shown to descend from F-theory on a specific class of Calabi-Yau fourfolds. In addition, mirror symmetry for Calabi-Yau orientifolds is briefly discussed and it is shown that the N = 1 chiral coordinates linearize the appropriate instanton actions.

Universität Hamburg, Diss., 2005; 128 pp., (2005). doi:10.3204/DESY-THESIS-2005-021, Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg