Higgs Decay into Two Photons at the Boundary of a Warped Extra Dimension

A detailed five-dimensional calculation of the Higgs-boson decay into two photons is performed in both the minimal and the custodially protected Randall-Sundrum (RS) model, where the Standard Model (SM) fields propagate in the bulk and the scalar sector lives on or near the IR brane. It is explicitly shown that the $R_\xi$ gauge invariance of the sum of diagrams involving bosonic fields in the SM also applies to the case of these RS scenarios. An exact expression for the $h\to\gamma\gamma$ amplitude in terms of the five-dimensional (5D) gauge-boson and fermion propagators is presented, which includes the full dependence on the Higgs-boson mass. Closed expressions for the 5D $W$-boson propagators in the minimal and the custodial RS model are derived, which are valid to all orders in $v^2/M_\textrm{KK}^2$. In contrast to the fermion case, the result for the bosonic contributions to the $h\to\gamma\gamma$ amplitude is insensitive to the details of the localization of the Higgs profile on or near the IR brane. The various RS predictions for the rate of the $pp\to h\to\gamma\gamma$ process are compared with the latest LHC data, and exclusion regions for the RS model parameters are derived.Comment: 30 pages (plus appendices), 4 figures (V2: several improvements of the discussion, discussion of the lepton sector added, typos corrected, references added

Analyses of production and decay processes of the Higgs boson and of a new scalar in a warped extra dimension

The thesis investigates the interactions of the Higgs boson and of a new scalar in a framework "beyond the Standard Model of particle physics", in which the Standard Model is embedded in a Planck-sized region of a five-dimensional anti-de Sitter space: the Randall-Sundrum model. A strong warping of all physical scales along the fifth dimension solves i.a. the gauge hierarchy problem. Mostly, a scenario of the Randall-Sundrum model is considered, in which all the particle fields including the Higgs field can extend into the five-dimensional space. It is proven that the predictions for Higgs processes lie significantly closer to the Standard Model's predictions, compared to realizations of the Randall-Sundrum model where the Higgs field is localized on a four-dimensional subspace at the end of the fifth dimension. Numerical evaluations of the various Higgs production and decay rates at the LHC are performed in dependence of the parameter space of the model and in comparison with experimental results from ATLAS and CMS. Furthermore, the implementation of a new, extra scalar field is elaborated in the Randall-Sundrum framework, by what the temporarily reported di-photon anomaly, seen as an excess of photon pairs in first 13 TeV data of the LHC, could conveniently be explained.Die Arbeit untersucht die Wechselwirkungen des Higgs-Bosons sowie eines neuen Skalars im Randall-Sundrum-Modell, in welchem das Standardmodell der Elementarteilchenphysik in einer fünfdimensionalen Anti-de-Sitter-Raumzeit der Größe der Planck-Skala eingebettet ist. Eine starke Raumkrümmung entlang der fünften Dimension kann u.a. eine Erklärung für das Eichhierarchieproblem geben. Vorrangig wird in dieser Arbeit ein Szenario des Randall-Sundrum-Modells betrachtet, in dem alle Teilchenfelder sowie das Higgsfeld sich in den vollen fünfdimensionalen Raum ausbreiten. Die damit gewonnenen Vorhersagen für Higgs-Prozesse liegen deutlich näher an denen des Standardmodells im Vergleich zu Szenarien mit einer Higgslokalisierung auf einem Unterraum am Rand der fünften Dimension. Higgsproduktions- und Higgszerfallsraten werden numerisch in Abhängigkeit vom Parameterraum des Randall-Sundrum-Modells ausgewertet, und mit experimentellen Resultaten von ATLAS und CMS verglichen. Im zweiten Teil der Arbeit werden Produktions- und Zerfallsprozesse eines zusätzlichen skalaren Feldes im Rahmen des Randall-Sundrum-Modells untersucht. Diese boten geeignete Erklärungen für die Anomalie von Photonenpaaren, die zunächst mit den ersten 13 TeV-Daten des LHC's gemessen wurde

Diphoton Resonance from a Warped Extra Dimension

We argue that extensions of the Standard Model (SM) with a warped extra dimension, which successfully address the hierarchy and flavor problems of elementary particle physics, can provide an elegant explanation of the 750 GeV diphoton excess recently reported by ATLAS and CMS. A gauge-singlet bulk scalar with ${\cal O}(1)$ couplings to fermions is identified as the new resonance $S$, and the vector-like Kaluza-Klein excitations of the SM quarks and leptons mediate its loop-induced couplings to photons and gluons. The electroweak gauge symmetry almost unambiguously dictates the bulk matter content and hence the hierarchies of the $S\to \gamma\gamma$, $WW$, $ZZ$, $Z\gamma$, $t\bar t$ and dijet decay rates. We find that the $S\to Z\gamma$ decay mode is strongly suppressed, such that \mbox{Br}(S\to Z\gamma)/\mbox{Br}(S\to\gamma\gamma)<0.1. The hierarchy problem for the new scalar boson is solved in analogy with the Higgs boson by localizing it near the infrared brane. The infinite sums over the Kaluza-Klein towers of fermion states are finite and can be calculated in closed form with a remarkably simple result. Reproducing the observed $pp\to S\to\gamma\gamma$ signal requires Kaluza-Klein masses in the multi-TeV range, consistent with bounds from flavor physics and electroweak precision observables. Useful side products of our analysis, which can be adapted to almost any model for the diphoton resonance, are the calculation of the gluon-fusion production cross section $\sigma(pp\to S)$ at NNLO in QCD, an exact expression for the inclusive $S\to gg$ decay rate at N$^3$LO, a study of the $S\to t\bar t h$ three-body decay and a phenomenological analysis of portal couplings connecting $S$ with the Higgs field.Comment: 31 pages, 7 figures, 3 tables; v2: typos fixed and some references added; v3: missing color factor in t tbar rates included and numerical results updated, extended discussion of the Higgs portal, version published in JHE

Daily AI-Based Treatment Adaptation under Weekly Offline MR Guidance in Chemoradiotherapy for Cervical Cancer 1: The AIM-C1 Trial

(1) Background: External beam radiotherapy (EBRT) and concurrent chemotherapy, followed by brachytherapy (BT), offer a standard of care for patients with locally advanced cervical carcinoma. Conventionally, large safety margins are required to compensate for organ movement, potentially increasing toxicity. Lately, daily high-quality cone beam CT (CBCT)-guided adaptive radiotherapy, aided by artificial intelligence (AI), became clinically available. Thus, online treatment plans can be adapted to the current position of the tumor and the adjacent organs at risk (OAR), while the patient is lying on the treatment couch. We sought to evaluate the potential of this new technology, including a weekly shuttle-based 3T-MRI scan in various treatment positions for tumor evaluation and for decreasing treatment-related side effects. (2) Methods: This is a prospective one-armed phase-II trial consisting of 40 patients with cervical carcinoma (FIGO IB-IIIC1) with an age ≥ 18 years and a Karnofsky performance score ≥ 70%. EBRT (45–50.4 Gy in 25–28 fractions with 55.0–58.8 Gy simultaneous integrated boosts to lymph node metastases) will be accompanied by weekly shuttle-based MRIs. Concurrent platinum-based chemotherapy will be given, followed by 28 Gy of BT (four fractions). The primary endpoint will be the occurrence of overall early bowel and bladder toxicity CTCAE grade 2 or higher (CTCAE v5.0). Secondary outcomes include clinical feasibility, quality of life, and imaging-based response assessment

Methods of Esthetic Assessment after Adjuvant Whole-Breast Radiotherapy in Breast Cancer Patients: Evaluation of the BCCT.core Software and Patients&rsquo; and Physicians&rsquo; Assessment from the Randomized IMRT-MC2 Trial

The present analysis compares the esthetics assessment by the BCCT.core software in relation to patients&rsquo; and physicians&rsquo; ratings, based on the IMRT-MC2 trial. Within this trial, breast cancer patients received breast-conserving surgery (BCS) and adjuvant radiotherapy. At the baseline, 6 weeks, and 2 years after radiotherapy, photos of the breasts were assessed by the software and patients&rsquo; and physicians&rsquo; assessments were performed. Agreement rates of the assessments and their correlation with breast asymmetry indices were evaluated. The assessments of the software and the physicians were significantly correlated with asymmetry indices. Before and 6 weeks after radiotherapy, the patients&rsquo; self-assessment was only correlated with the lower breast contour (LBC) and upward nipple retraction (UNR), while after 2 years, there was also a correlation with other indices. Only a slight agreement between the BCCT.core software and the physicians&rsquo; or patients&rsquo; assessment was seen, while a moderate and substantial agreement was detected between the physicians&rsquo; and the patients&rsquo; assessment after 6 weeks and 2 years, respectively. The BCCT.core software is a reliable tool to measure asymmetries, but may not sufficiently evaluate the esthetic outcome as perceived by patients. It may be more appropriate for a long-term follow-up, when symmetry appears to increase in importance