Higgs phenomenology in the Stealth Doublet Model

We analyze a model for the Higgs sector with two scalar doublets and a $Z_2$ symmetry that is manifest in the Yukawa sector but broken in the potential. Thus, one of the doublets breaks the electroweak symmetry and has tree-level Yukawa couplings to fermions, whereas the other doublet has no vacuum expectation value and no tree-level couplings to fermions. Since the $Z_2$ parity is broken the two doublets can mix, which leads to a distinct and novel phenomenology. This Stealth Doublet Model can be seen as a generalization of the Inert Doublet Model with a broken $Z_2$ symmetry. We outline the model and present constraints from theory, electroweak precision tests and collider searches, including the recent observation of a Higgs boson at the LHC. The charged scalar $H^\pm$ and the CP-odd scalar $A$ couple to fermions at one-loop level. We compute the decays of $H^\pm$ and $A$ and in particular the one-loop decays $A \to f \bar{f}$, $H^\pm \to f \bar{f}^\prime$, $H^\pm \to W^\pm Z$ and $H^\pm \to W^\pm \gamma$. We also describe how to calculate and renormalize such processes in our model. We find that if one of $H^\pm$ or $A$ is the lightest scalar, $H^\pm \to W^\pm \gamma$ or $A \to b \bar{b}$ are typically their respective dominating decay channels. Otherwise, the dominating decays of $H^\pm$ and $A$ are into a scalar and a vector. Due to the absence of tree-level fermion couplings for $H^\pm$ and $A$, we consider pair production and associated production with vector bosons and scalars at the LHC. If the parameter space of the model that favors $H^\pm \to W^\pm \gamma$ is realized in Nature, we estimate that there could be a considerable amount of such events in the present LHC data.Comment: 40 pages, 25 figures. Version 4. Minor updates, references added. Version to appear in PR

Eucharistic Hospitality in Ecumenical Contexts:Learning from Monastic Experiences

This practical theological study explores Eucharistic hospitality in the ecumenical monastic communities of Taizé, (Burgundy, France) and (Piedmont, Italy). Tracing the theology embedded in this practice, it offers empirically grounded insights into the dynamics of the Eucharistic hospitality and provides an innovative view on the sensus fidei on this point. As such, this study presents a relevant addition to the charged debate about this sensitive issue, challenging Roman Catholic theology to learn from the decades-long experience accumulated in the communities

The role of Wnt5 during Axon guidance

The main focus of this thesis is the study of the role of Wnt5 during central nervous system development in Drosophila. Wnt5, previously known as DWnt3, was identified as a gene required for proper central nervous system development. The finding that a Wnt protein, traditionally associated with other developmental functions, is also required for axon guidance during late embryogenesis provided exciting new insights in the broad mechanisms that are used to establish the stereotypical neuronal connectivity of the central nervous system. Subsequent experiments described in this thesis reveal that, during embryonic development of the central nervous system, Wnt5 seems to be acting through an alternative pathway which involves src mediated signaling through the fractured tyrosine kinase RYK/Drl. Furthermore, we show that Wnt5 signaling through RYK/Drl is also required for proper muscle development suggesting a common signaling pathway required for muscle attachment site selection as well as axon guidance.The work in this thesis was financially supported by the Netherlands Organization for Scientific Research (NWO) Financial support for the printing of this thesis was generously provided by: J.E. Jurriaanse Stichting, Koninklijke Nederlandse Academie voor Wetenschappen: Van Leersumfonds, Stichting Leids Universitair Fonds en Leica Microsystems Nederland b.v..UBL - phd migration 201