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Oberseminar SoSe 2016

Freitags       11:15 - 12.15 Uhr        SR 7
Contact:   dbuarqu at gwdg . de (or) Zinonas . Zinonos at phys . uni-goettingen . de
A. Frey, H. Hofsäss, S. Schumann, A. Quadt, S. Lai






Jörn Grosse-Knetter

Sicherheitsbelehrung - Safety Briefing


Dr. Peter Wagner
University of Bonn

Particle Flow Reconstruction of Tau Lepton Decays and Analysis Prospects

Final states with hadronically decaying tau leptons play an important part in the physics programme of the ATLAS experiment. Examples are measurements of Standard Model processes, evidence of the Higgs-boson Yukawa couplings to tau leptons, and searches for new physics phenomena, such as Supersymmetry. These analyses depended on robust tau reconstruction and excellent particle identification algorithms that provided suppression of backgrounds from jets, electrons and muons. I will present a new "particle flow" method of reconstructing the individual charged and neutral hadrons in tau decays with the ATLAS detector which leads to a significant improvement in the tau energy and directional resolution. It further gives access to the individual charged and neutral hadron four-momenta and offers a high purity decay mode selection. These features will play a particularly important role in analyses that exploit tau spin information, such as a measurement of the CP mixture of the Higgs boson in Higgs to ditau decays.


Tobias Bisanz
Universitaet Goettingen, II. Physikalisches Institut

Code Quality: Modern C++


Day after Ascension


Joshua Wyatt Smith
Universitaet Goettingen, II. Physikalisches Institut

Code Quality 2


Dr. Louis Helary
Boston University and CERN

Review of recent Electroweak results from the LHC.

In this talk the recent results from the LHC on Electroweak physics will be reviewed using LHC-run1 or run2 data. In particular will be presented: measurement of single boson production via vector boson fusion, precise extraction of Standard Model Electroweak parameters, precise measurement of di-boson final states, searches for vector boson scattering, and searches or observation of tri-boson final states. Interpretations of these measurements to constrain new physics scenarios in a model independent way will also be discussed.





Dr. Marek Schoenherr
University of Zuerich

Electroweak corrections for the LHC

In this talk I am going to present recent results regarding the NLO electroweak corrections for vector boson production in association with jets. Besides discussing the phenomenology of the fixed-order results I will outline how they can be incorporated in existing NLO QCD parton shower matched and merged calculations which can directly be used in experimental analyses.


(CANCELED) Dr. Tobias Flick
Universität Wuppertal

Phase-2 upgrade of the ATLAS tracker readout

The ATLAS inner detector will be replaced by a new tracker, called Inner Tracker (ITk), during phase II upgrade around 2023. The new tracker will be purely silicon based and cover an area of 200 m2 equipped with strip modules for the outer region and pixel modules for the inner region. As the HL-LHC will increase luminosity but not energy, the particle hit rate will be increased and therefore the hit occupancy of the detector will increase a lot. Smaller pixel to provide a better granularity and better resolution as well as faster data transfer to keep deadtime as low as possible are some consequences. The new FE-ASIC which is under development needs to transfer data extremely fast to the outer world. Therefore, a completely new readout system has to be developed as well. The talk will describe the background of detector readout and will focus on the new ATLAS ITk pixel readout.


Dr. Alexander Oh
Manchester University

3D diamond detectors for particle tracking and dosimetry

Advances in the laser assisted transformation of diamond into amorphous-carbon has enabled the production of a new type of particle detector - 3D diamond. Compared to conventional planar technologies, previous work has proven a 3D geometry to improve the radiation tolerance of detectors fabricated in silicon. First tests of single-crystal and polycrystalline CVD diamond 3D detectors in various particle beams and performance comparison with simulations demonstrate the viability of this concept. Recent improvement in the fabrication methods, including the use of a spatial light modulator to produce conductive wires with ~1um diameter allowed the fabrication of devices in both single-crystal and polycrystalline CVD diamond with lower resistivity of the wires, promising an improved performance. Furthermore the use of spatial light modulators open up the possibility of arbitrary wire shapes and therefor new detector concepts. Outside the field of high energy particle physics, a potential application for this technology includes medical dosimetry; where the high resilience to radiation damage, operation at low bias voltage with well defined active volume, in addition to high compatibility to human tissue, makes their use desirable. First tests with at an clinical irradiation facility show promising results.


Prof. Volker Metag
Justus-Liebig-Universtät Gießen

Experimental tests of QCD at the low energy frontier

While the mass of elementary particles is given by their interaction with the Higgs field, the mass of hadrons (protons, neutrons) and thus the mass of matter around us and in the visible universe is determined by the strong interaction (Quantum Chromodynamics: QCD). In the GeV energy regime, i.e. at the low energy frontier, the coupling strength αs of the strong interaction is close to 1.0. Consequently, perturbative treatments successfully applied in the high energy domain, where αs (100 GeV) ≈ 0.1, fail to describe the relevant phenomena. The origin of hadron masses and their predicted modification in a strongly interacting medium like in an atomic nucleus are key issues in understanding QCD in the strong coupling regime. Hadron properties are either calculated with lattice QCD or QCD inspired hadronic models. For a test of these models, experiments have been performed to determine the properties of mesons in nuclei. The in-medium properties of ω and η’ mesons have been studied in photo production off nuclear targets at the ELSA accelerator (Univ. Bonn) using the CBELSA/TAPS detector system. Results on the in-medium mass and width of the ω and η’ meson and the meson-nucleus optical potential will be presented. For the first time a mass drop of the η’ meson by about 40 MeV at normal nuclear matter density has been observed. The real part of the optical potential is found to be much larger than the imaginary part; this makes the η’ meson a promising candidate to form meson-nucleus bound states. Ongoing searches for η’ mesic states will be discussed.


Prof. Mads Frandsen
CP3-Origins, Southern University of Denmark

Dynamical electroweak symmetry breaking in light of LHC results


Christoph Englert
Glasgow University

Effective Theories at the LHC

I will discuss the implications of recent LHC Higgs and top quark measurements from an Effective Field Theory perspective. In particular I will highlight the importance of differential distributions in obtaining stringent constraints on the potential presence of new physics beyond the Standard Model.


BSc students
University of Göttingen

Presentations by BSc students


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