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Oberseminar WiSe 2016-17

Freitags       11:15 - 12.15 Uhr        SR 7
Contact:   dbuarqu at gwdg . de
A. Frey, H. Hofsäss, S. Schumann, A. Quadt, S. Lai






Prof. H. Hofsäss

Sicherheitsbelehrung - Radiation Safety Briefing


Dr. Flavia Dias
University of Edinburgh

Fast simulation/ new physics


Dr. Frank Siegert
University of Dresden

A practical guide to event generation for prompt photon production








Dr. Quentin Buat
Simon Fraser University



Arnaud Ferrari, Associate professor
University of Uppsala

Searches for beyond-the-Standard Model Higgs bosons in ATLAS


Dr. Felipe Bregonlin
II. Physikalisches Institut Goettingen

Development of an efficient high current ion source for Accelerator Mass Spectrometry


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. Ben Nachman
Lawrence Berkeley National Laboratory

Grand Challenges for Jet Substructure

The radiation pattern within high energy jets contains a wealth of information about the properties of the initiating particle. Use of this jet substructure has attracted considerable attention at the LHC and is used by many high profile searches. This talk describes the key challenges in reconstructing jet substructure and new ideas for improving the discrimination power, resolution, and modeling of our observables.


Prof. Juergen Reuter

Searching New Particles in Vector Boson Scattering at the LHC

After the discovery of a light Higgs boson at the LHC in 2012, the scattering of weak vector bosons has become an even bigger vehicle as search for new physics beyond the Standard Model. After reviewing the status of measurements at the LHC, we will show that model-independent searches in terms of effective field theories are ill-suited in that channel. To remedy this, we introduce simplified models of scalar and tensor particles in the diboson scattering channel and discuss their physics. Prospects for the upcoming runs at the LHC will be given (as well as for future high-energy lepton colliders). Some open theoretical issues will be reviewed.


Prof. Steve Muanza
Marseille University

Using integral and differential charge asymmetries in searches for BSM physics at the LHC

Contrarily to past high energy colliders, the LHC is a charge asymmetric machine. Therefore most of the hard scattering processes producing electrically charged final states have a positive integral charge asymmetry. The latter quantity, denoted AC, is easily measurable in event topologies bearing an odd number of hard and isolated charged leptons. We have brought to light the strong correlation between AC and the mass of the charged final state. This enabled us to setup a new method of indirect mass measurement [1]. For example, this method enables to measure the mass of the W boson with a 2% accuracy. Obviously this is not competitive with respect to the standard technique based on the W transverse mass. However for other processes where more final state particles escape detection, we've demonstrated the integral charge asymmetry method to be much more effective. We illustrate this in a search for a supersymmetric production of chargino-neutralino pairs decaying in the trilepton inclusive topology and show that we can measure M(chargino)+M(neutralino) with an accuracy better than 10%. Nevertheless, in order to apply the integral charge asymmetry method, one needs to have a significant excess of signal events over the event yield of the corresponding background processes. We are currently extending this indirect mass measurement method using differential charge asymmetries. In addition to their sensitivity to the mass, the shape of these observables can also be exploited to improve the separation between a signal and its background processes. Our main physics case under study is the production of an heavy W' boson which decays into a single charged lepton plus missing transverse energy. For both the use of integral and differential charge asymmetries we are also developing quantitative estimates of their sensitivity through appropriate confidence levels. [1] S. Muanza and T. Serre, "New Method for Indirect Mass Measurements using the Integral Charge Asymmetry at the LHC", JHEP 1604 (2016) 179, arXiv:1412.6695 [hep-ph].



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