IRTG PhD days 2012

9 Oct 2012, 09:00 → 10 Oct 2012, 23:00 Europe/Berlin

Seminar room 2, building 2a, ground floor (Desy)

Benedikt Vormwald (DESY Hamburg), Falk Lindner, Julia Harz (DESY Hamburg), Madalina Chera (DESY), Reinke Sven Isermann (II. Institut fuer Theoretische Physik, Univ. Hamburg)

The Collaborative Research Center 676 (SFB 676) at Hamburg University and the cluster of excellence LEXI at Hamburg University and DESY are research programs at the interface of particle physics, string theory and cosmology. Significant developments are taking place in each of these fields, and far-reaching scientific results are expected in the course of the next 20 years.

Many PhD students are involved in the different SFB and LEXI research fields and organized in a structured graduate program, the “Integrated Research Training Group” (IRTG). In order to benefit from the given experience in different fields, this two-days workshop is meant to bring PhD students and experienced international researchers together and create a platform for discussions, exchange and new ideas.

Besides main lecture courses given by highly experienced speakers, PhD students will get the opportunity to present and discuss their own work related to the SFB and LEXI research topics.

Tuesday 9 October

Morning Lecture 1

1 Welcome

2 Quantum information and computation: foundations and current status - part 1

In recent years we've seen the birth of an exciting new field known as quantum information (QI) theory. In these lectures I will introduce the basic concepts of QI, namely, qubits, quantum circuits, and quantum algorithms. I will also introduce some of the guiding problems of the field and describe recent applications of QI concepts to the study of strongly correlated physics.

Speaker: Prof. Tobias Osborne (University of Hannover)

11:00 coffee break

3 Quantum information and computation: foundations and current status - part 2

In recent years we've seen the birth of an exciting new field known as quantum information (QI) theory. In these lectures I will introduce the basic concepts of QI, namely, qubits, quantum circuits, and quantum algorithms. I will also introduce some of the guiding problems of the field and describe recent applications of QI concepts to the study of strongly correlated physics.

Speaker: Prof. Tobias Osborne (University of Hannover)

13:00 lunch break

Student session

4 IRTG - Integrated Research Training Group

Speaker: Dr Marco Baumgartl (Uni Hamburg)

5 DoIt

Introduction and report from DoIt.

Speaker: Mr Christian Pfeifer (II Institute for Theoretical Physics, Uni Hamburg)

6 The road to ALPS II -- an experimental update

The short talk will be an update of the talk last year. Main topics are the ALPS II experiment, the goals and status, the experimental process, and the status of the single photon detector (TES).

Speaker: Mr Jan Dreyling-Eschweiler (DESY)

Slides 2012_phd-days_dreyling-eschweiler.pdf

7 Off-shell effects in new physics cascades

New physics are highly anticipated to be observed in the near future at the LHC. Immediately ensuing a discovery is the determination of intrinsic properties such as masses and spins of new particles. However, many measurements rely on fundamental assumptions, which need not necessarily be fulfilled. One such possibility is a broad resonance at the beginning of a new physics cascade. Using the gluino as an example, we study the implications of off-shell contributions on mass and spin measurements and determine to what extent a discrimination between fundamentally different models is at stake.

Speaker: Mr Daniel Wiesler (DESY)

Slides offshell.pdf

15:30 coffee break

8 Think outside the BOX

Wednesday 10 October

Morning Lecture 2

9 Neutrino Physics - part 1

In these lectures, I discuss three aspects of neutrino physics: neutrino oscillations, neutrino mass, and neutrino astrophysics. In neutrino oscillations, the recent measurement of the mixing angle theta13 has opened the possibility to discover leptonic CP violation, which would motivate the possibility that the baryon asymmetry of the universe is connected with neutrino physics. I discuss the current understanding of neutrino oscillations and briefly comment on the future perspectives. As far as neutrino mass is concerned, I focus on questions such as: Are massive neutrinos to be interpreted as physics beyond the Standard Model? What model ingredients are needed if neutrino mass is connected with physics as the TeV scale, and thus potentially observable at the LHC? What kind of "new physics" may be showing up in the neutrino sector only? What does the discovery of a large theta13 mean for the theory of flavor? In neutrino astrophysics, I highlight the possibility to test the sources of the ultra-high energy cosmic rays with neutrinos, and I illustrate how neutrino oscillations in the Sun work.

Speaker: Dr Walter Winter (Universitaet Wuerzburg)

11:00 coffee break

10 Neutrino Physics - part 2

In these lectures, I discuss three aspects of neutrino physics: neutrino oscillations, neutrino mass, and neutrino astrophysics. In neutrino oscillations, the recent measurement of the mixing angle theta13 has opened the possibility to discover leptonic CP violation, which would motivate the possibility that the baryon asymmetry of the universe is connected with neutrino physics. I discuss the current understanding of neutrino oscillations and briefly comment on the future perspectives. As far as neutrino mass is concerned, I focus on questions such as: Are massive neutrinos to be interpreted as physics beyond the Standard Model? What model ingredients are needed if neutrino mass is connected with physics as the TeV scale, and thus potentially observable at the LHC? What kind of "new physics" may be showing up in the neutrino sector only? What does the discovery of a large theta13 mean for the theory of flavor? In neutrino astrophysics, I highlight the possibility to test the sources of the ultra-high energy cosmic rays with neutrinos, and I illustrate how neutrino oscillations in the Sun work.

Speaker: Dr Walter Winter (Universitaet Wuerzburg)

13:00 lunch break

Student session

11 Particle Flow Performance Studies at ILC

The physics program of the planned International Linear Collider (ILC) focuses on very high precision in measurements and searches of physics beyond the Standard Model. This places a strong demand on the ILC detectors' performance. One of the competing detector designs is the International Large Detector (ILD) which has been particularly optimised for the concept of particle flow reconstruction, using a GEANT4 based detector simulation. In order to reduce the CPU runtime necessary to obtain the large statistics for studying the physics reach of the ILC, a faster and more economic solution is needed. The Simulation a Grande Vitesse (SGV) is a fast detector simulation which determines the tracker response for any given detector geometry from first principles. This talk will describe the parametrisations implemented in SGV with the goal of making the fast simulation compatible with the particle flow paradigm.

Speaker: Madalina Chera (DESY)

Slides Madaphd_days.pdf

12 Linear colliders and the Furry Picture: How to deal with strong external fields.

Future linear colliders like ILC and CLIC could be powerful machines for the discovery and the precision study of new physics Beyond the Standard Model. Due to the intense beams (high luminosity, high energy), strong fields may occur in the beam interaction region where the physical processes take place. In the context of precision HEP, the presence of these strong fields may yield sensitive corrections to the observed electron-positron processes. We are studying this intense external field corrections through the Furry picture of quantum states in order to understand their significance, also in the light of BSM searches.

Speaker: Stefano Porto (Hamburg University)

Slides Stefano_PhDDays2012.pdf

13 Scattering Amplitudes in Strongly Coupled N=4 Super Yang-Mills

In this talk, I will investigate scattering amplitudes in strongly coupled N=4 Super Yang-Mills. To leading order, the amplitude at strong coupling is given in terms of a minimal surface in AdS5. The area of this surface can be calculated by a set of non-linear integral equations, which, however, do not allow an analytic solution for arbitrary kinematics. I will demonstrate that for special kinematics these equations simplify drastically and become algebraic equations, which are closely related to algebraic Bethe ansatz equations.

Speaker: Mr Martin Sprenger (DESY)

Slides talk_martin.pdf

15:30 coffee break

14 Thermal equilibrium states in quantum field theories

I review the approaches to descriptions of thermal equilibrium states in both quantum mechanics and quantum field theory. I argue, that the description via (Gibbs) density functionals is not sufficient to describe thermal equilibrium states in generic situations. I show a generalization of Gibbs states, the so-called KMS-states, and their application to quantum field theory.

Speaker: Mr Falk Lindner (II. Institute for Theoretical Physics, University of Hamburg)

Slides vortrag-falk.pdf

15 A generalization of States of Low Energy on Globally Hyperbolic Spacetimes

The fact that the renormalized energy density smeared along a timelike curve on a globally hyperbolic spacetime possesses a lower bound stimulates the pursuit of an explicit construction of a state whose energy is minimal. Such a task was completed for Robertson-Walker spacetimes and these states were named States of Low Energy. In this communication we construct such states for more general spacetimes and show which obstacles prevent a completely general construction.

Speaker: Mr Marcos Brum (Hamburg University)

Slides seminar_Brum.pdf

16 tba

Speaker: Mr Jan Heisig (University of Hamburg)

17 Interference effects in the MSSM

The ``narrow-width approximation'' is a convenient tool for the factorisation of a more complicated process into production and subsequent decay of a particle with a small width compared to its mass. However, this approximation cannot be applied in the case of sizable interferences between propagator contributions of different particles that are close to their mass shell. This may be relevant in models with an enlarged spectrum containing particles with a mass difference of the order of their decay widths. In order to deal with such a situation, a generalisation of the usual narrow-width approximation is analysed which allows for a consistent treatment of interference effects between such nearly mass-degenerate particles. This can be useful for the application to processes for which the factorisation into different sub-processes will be essential to enable the computation of higher-order contributions. Phenomenological consequences with interference effects between neutral MSSM Higgs bosons will be discussed for the example process of Higgs boson production and subsequent decay from the decay of a heavy neutralino.

Speaker: Elina Fuchs (DESY)

Slides ElinaFuchs-PhDDays2012.pdf

group photo of IRTG

18:30 break

Evening lecture

18 Physics and Nuclear Disarmament: Political and Technical Challenges of a World free of Nuclear Weapons

After the end of the Cold War, there was much hope that nuclear weapons can be reduced drastically. Despite some arms control successes, nuclear weapons still play a major role in world politics. The high nuclear arsenals between the USA and Russia are still based on Cold War doctrines facing new challenges such as the introduction of Ballistic Missile defense and precise conventional strike systems. technical expertise is necessary to analyse nuclear dismantlement and deep cuts in nuclear stockpiles, as well as the verification of fissile materials and the remocal of tactical nuclear weapons. The dispute on Iran´s ambivalent nuclear programmes reveals the thin line between civilian and military applications. Additional scientific-technical measures are necessary to strengthen non-proliferation and arms export control. The talk presents what scientists have done in the past to apply there skills for arms control and disarmament. Finally, the talk describes the scientific challenges of a world free of nuclear weapons and gives some examples of physical methods.

Speaker: Prof. Götz Neuneck (University of Hamburg)

Barbecue