Outline

Hadron accelerators will play a leading role in particle physics during the next 10-15 years. With the Large Hadron Collider (LHC), currently starting to take data at the European research centre for particle physics, CERN, in Geneva, an exploration of the so far unknown TeV energy domain will become possible very soon and answers to key questions of particle physics may become available.

The main topic of the proposed research programme is a test of the Standard Model of particle physics and the search for extensions at present and future hadron accelerators. In a first phase, tests of the electroweak theory and of Quantum Chromodynamics will be carried out with complementary measurements in different experiments. The experimental programme consists in the investigation of deep inelastic lepton nucleon scattering at the experiments ZEUS at DESY in Hamburg and COMPASS at CERN and in the investigation of proton antiproton collisions in the DØ experiment at the US research laboratory Fermilab as well as proton proton collisions in the ATLAS experiment at CERN.

An important part of the proposed programme is the calculation of 2-loop corrections for WW and Higgs production at hadron colliders. These calculations are necessary for a precise comparison between data and theory. Due to a close collaboration between physicists of different experiments on the one side and between experimentalists and theorists on the other side, an extensive analysis of current data can be carried out and the data analysis at the LHC can be prepared in an optimal way.

For Members of the Graduiertenkolleg

• Complete list of members
• List of GK events
• Seminar
• Lectures
• Annual meeting
• Continuing education
• Regulations (Promotionsordnung)
• Forms

For Applicants of the Graduiertenkolleg

• Research profile
• PhD topics
• Contact
• Application

For Visitors of the Graduiertenkolleg

• Research profile
• Contact

Members of the Graduiertenkolleg

Application

The Graduiertenkolleg started in April 2005. Applications for acceptance into the Graduiertenkolleg may be submitted anytime. Fellowships will be awarded to fill vacant PhD and postdoc position of the Graduiertenkolleg. It is recommended that applicants contact prospective supervisors and discuss their dissertation proposal prior to submitting a formal application. Details on the fellowships can be given on request and can also be inferred from the Deutsche Forschungsgemeinschaft DFG (FAQs in English/German language).

Applicants

Applicants for the fellowships should:

• be no older than 28 years (exceptions are possible if particular reasons exist);
• have an academic degree equivalent to a Diploma or a Master in Physics;
• be prepared to take an active part in the work of the Graduiertenkolleg.

Applications

Applications are accepted in German or English and should contain:

• a letter of application (no formal requirements) ;
• the names, addresses, and e-mail addresses of two persons (typically professors) who would be willing to send a letter of reference;
• a CV with emphasis on the academic career;
• a copy of all university certificates;
• a copy of a written diploma thesis or equivalent

Applications must be sent to this address:

Prof. Dr. Karl Jakobs
University of Freiburg
Physikalisches Institut
Hermann-Herder Str. 3
D-79104 Freiburg im Breisgau

Continuing Education

As a member of the Graduiertenkolleg you may take advantage of the offered programme for continuing education (e.g. language courses)

You may have a look at the following links:

• Akademie für wissenschaftliche Weiterbildung (in german)
• International Graduate Academy (IGA)
• Language Teaching Centre (SLI)
• Studium Generale (in german)

Graduiertenkolleg forms

• Antrag auf Mitarbeit als Kollegiat/in im Graduiertenkolleg (pdf, doc)
• Statistik Info, für ausscheidende Kollegiaten (pdf)

Possible PhD topics

Test of the Standard Model (COMPASS, DØ, ZEUS, theory)

• Measurement of the tt production cross section at the Tevatron
• Study of WW pair production at the Tevatron;
• Measurement of V_tb in single top production at the Tevatron;
• Measurement of the single top quark production cross section;
• Measurement of the W boson helicity in top quark decays;
• Measurement of the Top quark mass;
• Study of jet-jet correlations with BFKL signature at HERA;

The Structure of hadrons (COMPASS, ZEUS, Theory)

• Determination of the gluon polarization in COMPASS;
• Azimuthal asymmetries of pions and kaons in COMPASS;

Search for the Higgs boson (ATLAS, DØ, Theory)

• Search for the Higgs boson at the Tevatron in the H →W W → ℓnu ℓnu decay mode;
• Investigation of the Higgs boson discovery potential at the LHC using NLO Monte Carlo simulations for signals and backgrounds;
• Validation of new Monte Carlo programs, including a comparison to Tevatron data; 
• Studies on tau reconstruction  in ATLAS using full simulation;

Search for Physics beyond the Standard Model (ATLAS; DØ, theory)

• Search for charginos and neutralinos in the three-lepton decay mode in the DØ experiment;  
• Search for SUSY particles in final states with tau leptons in DØ;
• Determination of SUSY parameters at the LHC;

Theory

• Calculation of NNLO crosssections for WW-, WZ-, and ZZ production;
• Calculation of the NLO crossection for HH production at Hadron-colliders w.r.t finite top quark mass;
• Coherent states in deformation quantization.
  

Research programme

Experiments

The experimental particle physics groups at the University of Freiburg are currently engaged in the following experiments:

• The ATLAS experiment at the LHC:
  The focus during the past years was on the detector construction in the areas of the silicon tracking and muon detector systems. In parallel, studies on the physics potential in the search for Higgs bosons and Supersymmetry have been performed.
• The COMPASS experiment at the CERN super proton synchrotron
• The DØ experiment at the Tevatron ppbar Collider:
  The activities are concentrated on the analysis of data taken in the ongoing run. Central topics are the search for the Standard Model Higgs boson and for supersymmetric particles as well as the measurement of parameters of the top quark.
• The ZEUS experiment at DESY

Theory

Research programme of the Graduiertenkolleg

Within the Graduiertenkolleg  „Physics at Hadron Coliders“ important tests of the Standard Model will be carried out in the experiments at existing hadron colliders.  Perturbative QCD will be tested in deep inelastic scattering at HERA and in the COMPASS experiment. In the DØ experiment, top-quark and vector boson pair production will be studied and the measurements will be compared to QCD predictions. In addition, non-perturbative aspects of QCD will be addressed in the COMPASS experiment. In the electroweak sector, precise measurements of the mass of the top quark and of the coupling parameter Vtb are foreseen to be carried out in the DØ -and later- in the ATLAS experiment.

An important part of our research activities represents the search for the Higgs boson and for extensions beyond the Standard Model, in particular supersymmetry, in both the DØ and the ATLAS experiment. Final states with leptons and missing transverse momentum are considered. This includes the tau-lepton signature, for which efficient reconstruction and tagging algorithms have still to be developed.

On the theoretical side the calculation of higher order corrections for WW and Higgs pair production at hadron colliders is the main focus.

Within the Graduiertenkolleg a close collaboration between the theory and experiment on one side and between the various experiments on the other side is foreseen. An example of such a collaboration is the calculation of higher order QCD corrections for important signal and background processes for Higgs boson searches, their implementation in Monte Carlo generators and a first comparison –at least for the background processes- with Tevatron data. Precise estimates of cross sections at the LHC rely on precise measurements of the proton structure, as  determined at  HERA and COMPASS.

The whole research programme is subdivided into four main areas:

1. Test of the Standard Model  (COMPASS, DØ, ZEUS, theory)
2. The Structure of hadrons  (COMPASS, ZEUS, Theory)
3. Search for the Higgs boson (ATLAS, DØ, Theory)
4. Search for Physics beyond the Standard Model (ATLAS; DØ, theory)

Klausurtagung

2009:

The "Klausurtagung" is an internal meeting for all members of the Graduiertenkolleg. This year's Klausurtagung was held from 10th to 12th December at Feldberg. The preliminary schedule can be downloaded here. You can browse the lectures here.

2008:

This year's Klausurtagung was held at the Feldberg from 11th to 13th December. The program can be downloaded here.

The slides of the students' talks and the lecture can be found here.

NOTE: This material is protected by a password and should only be accessible to members of the Graduiertenkolleg. There is also a gallery of photos taken at the Klausurtagung. Right now they are also protected.
If you want access to these protected materials or if you want to have something removed you should write an email to the Webmaster.

Former Meetings:

Information about former meetings can be found here:

• 2005
• 2006
• 2007

Contact

Seminars:

NEW: The Gaduiertenkolleg seminar usually takes place on Wednesday (every two weeks) at 5 pm (c.t.) in HS2.

Schedule for next semester: The list of dates, speakers and topics is not yet complete. Please check for updates!

SS 2010

WS 2009/2010

SS 2009

WS 2008/09

Talks from previous semesters can be found here.

Thomas Reiter

Tools for One-Loop Calculations

Special Seminar, 3.3.2010

The main collider experiments currently running are hadron colliders where the most dominant reactions are due to the strong interaction. Any predictions for these experiments therefore have to account for the fact that cross-sections calculated in QCD suffer from large renormalisation scale uncertainties and often it is inevitable to calculate the observables beyond leading order for processes with three and more final state particles. Part of the scattering amplitude at next-to-leading order are the virtual corrections consisting of Feynman diagrams with one loop.

I discuss tools and techniques to automatise such computations and present the GOLEM method for one-loop calculations. This method is based on Feynman diagrams and the semi-numerical reduction of one-loop tensor integrals. A general matrix element generator for one-loop amplitudes is currently being developed in this framework and has led to results which I present in the last part of this talk.

Steffen Schumann

QCD Matrix Elements and Truncated Showers

Seminar, 8.4.2009

A realistic theoretical modelling of multijet final states in collider experiments is crucial for our understanding of this interesting class of experimental signatures. I will discuss the approach of combining QCD matrix elements with parton shower simulations -- used by modern Monte Carlo event generators. I will present recent theoretical achievements to reduce and systematise the uncertainties inherent in these calculations. As practical example I will discuss weak gauge boson production both in the Drell-Yan and the vector-boson-fusion channel.

Christian Speckner

s Channel Production of Heavy Vector Bosons in the Three-Site Higgsless Model

Sonderseminar, 8.4.2009

The Three-Site Higgsless model is an interesting example of higgsless BSM model building in which unitarity of scattering amplitudes is maintained by additional heavy vector bosons. The couplings between these and the standard model fermions are very small and strongly constrained by electroweak precision observables. I investigate the possibility of producing these heavy vectors in the $s$ channel at the LHC.

Luca Panizzi

One-Loop Electroweak Analysis of (S)Top Production Processes at LHC

Sonderseminar, 29.7.2009

A thorough analysis of third family (s)particles will soon be performed at the LHC. Since the LHC will produce top quarks with high statistics, this particle will extensively be exploited for new physics searches. On the other hand, the supersymmetric partner of the top quark, the stop squark, is predicted to have a sufficiently low mass to be produced and detected at the LHC. Providing experimentalists with precise predictions on observables related to meaningful top and stop production processes is therefore mandatory. In this talk the one-loop electroweak corrections to two processes of production of top and stop at the LHC, namely PP→ tH- and PP→ stop chi-, will be analysed.

Giovanni Balossini

Combining electroweak and QCD corrections to single W production at hadron colliders

Sonderseminar, 29.7.2009

Single W production is a process of relevant physical interest at hadron colliders, since it should be used to perform precise measurements of the electroweak parameters, to constrain PDFs, for monitoring the luminosity and calibrating the detectors. Furthermore, it provides a background to new physics signals. Precision studies of this process require that electroweak and QCD higher-order contributions are simultaneously taken into account in theoretical predictions and data analysis. Therefore, a phenomenological study of both of them, as well as of their combination by means of a proper theoretical recipe, is presented, with emphasys on the relevant observables for the Tevatron and LHC physics programme.

Matthias Grosse Perdekamp

Proton Spin Structure and Spin-Dependent Effects in Quark Fragmentation

Seminar, 24.06.2009

The Collins effect in hadron fragmentation describes a correlation between the transverse spin of the initial quark and the orbital angular momentum of final state hadrons. We present measurements of the Collins effect in electron-positron annihilation at KEKB using the Belle detector and show how this measurements can be used to determine the quark transversity distributions of the proton.

Jochen Hartert

RADMON

Seminar, 15.10.2008

In LHC experiments, a precise measurement of the radiation dose at various detector locations is crucial. In ATLAS, this task is performed by a set of radiation monitors (RADMON) which are able to record Non-Ionising Energy Loss (NIEL), the Total Ionizing Dose (TID) and measure fluences of thermal neutrons. These measurements are vital for understanding the changes in detector performance during ATLAS operation, verifying simulations and optimising the operation scenario. The RADMONs are multi-sensor boards, containing several RADFETs, diodes and DMILL transistors.

Helmut Burkhardt

The LHC Machine

Seminar, 29.10.2008

The LHC machine was recently completed and commissioning with beams started. The large project and some of its main challenges will be reviewed. The talk will then focus on the first observations with beams in the LHC, the current status, further commissioning plans and end with a short outlook into longer term perspectives.

Daniel Froidevaux

Expected performances of ATLAS and CMS experiments at the LHC

Seminar, 12.11.2008

After a short historical introduction to put into perspective the scope of the LHC experiment endeavour, the talk will focus on the major design choices made for the ATLAS and CMS experiments. Now that the detectors are installed and commissioned ten-fifteen years after these choices were made, it is interesting to review the performances expected in terms of reconstruction and identification of the basic physics objects of interest (tracks, electrons, photons, muons, tau- leptons, jets, ETmiss).

Per Grafstrom

Luminosity Measurements in ATLAS

Seminar, 26.11.2008

Different methods to determine the luminosity for the ATLAS experiment at the LHC will be discussed. Physics processes with a potential to be used for absolute luminosity determination will be discussed. The option of using accelerator parameters to calculate the luminosity will also be addressed. ATLAS Forward Detectors to be used for absolute luminosity determination as well as a detector for relative luminosity measurement will be described. The expected precision in different methods will be evaluated.

Lectures:

WS 2009/10

Giampiero Passarino (Universita di Torino):
A Layman's Guide to Two Loops

SS 2009

Helge Voss (MPI-K, Heidelberg):
Multivariate Data Analysis and Machine Learning in High Energy Physics

Multivariate classification and regression techniques are becoming increasingly important for high energy physics experiments with ever larger data samples allowing to assess events with ever smaller cross section. This lecture will explain the basic principles of machine learning and introduce the most common multivariate statistical methods. The behaviour of the individual classifiers is demonstrated using example applications. During the accompanying exercises, the TMVA program package is used in order to gain hands on experience in the proper training and evaluation of various classifiers.

To find the locations: See here

WS 2008/09

You should also take a look at the following links :

• Career Center of the University
• Studium Generale
• Foreign language learning (Sprachlehrinstitut)
• International Graduate Academy
• Center for Soft Skills

Lectures from previous semesters can be found here.