Past activities

December's Bethe Colloquium took place on 16. December (3:15 pm):

• Andrzej J. Buras    (TU Munich)
• Searching for New Physics at Very Short Distance Scales with Flavour Physics
• Hörsaal I, Physikalisches Institut

Abstract: After an introduction to the Standard Model of elementary particle interactions, I will give several arguments why particle physicists expect New Physics, represented by new forces and new particles, at scales of order 10^-19 m to be explored soon by the Large Hadron Collider (LHC) at CERN. Low energy precision measurements of quark and lepton flavour violating processes, in particular those involving the violation of CP symmetry, represent an alternative route to very short distance scales. Governed by quantum fluctuations they can provide in this decade insights into the distances explored by the LHC and even significantly shorter distance scales. Recent advances in this field will be reviewed in a non-technical manner.

BCTP member Prof. Herbi Dreiner, Prof. Howard Haber, and Prof. Stephen Martin jointly published a book on "Two-component spinor techniques and Feynman rules for quantum field theory and supersymmetry" in Physics Reports. During the final preparation, Humboldt prize laureate Prof. Howard Haber was a guest at the BCTP.

• Herbi Dreiner    (BCTP Bonn University)
• Howard Haber    (University of Caifornia, Santa Cruz)
• Stephen Martin    (Northern Illinois University )

Abstract: Two-component spinors are the basic ingredients for describing fermions in quantum field theory in 3+1 spacetime dimensions. We develop and review the techniques of the two-component spinor formalism and provide a complete set of Feynman rules for fermions using two-component spinor notation. These rules are suitable for practical calculations of cross-sections, decay rates, and radiative corrections in the Standard Model and its extensions, including supersymmetry, and many explicit examples are provided. The unified treatment presented in this review applies to massless Weyl fermions and massive Dirac and Majorana fermions. We exhibit the relation between the two-component spinor formalism and the more traditional four-component spinor formalism, and indicate their connections to the spinor helicity method and techniques for the computation of helicity amplitudes.

The 2nd Bethe Center Workshop which was jointly organised with the Transregio 33 – The Dark Universe included a meeting of the gender board. There is a podcast by uni-bonn.tv about this meeting and gender issues in physics, featuring BCTP members Nana Cabo Bizet and Ivonne Zavala.

           

November's Bethe Colloquium took place on 18. November (3:15 pm):

• Pavel Kroupa    (Argelander Institute for Astronomy, Bonn)
• Simon White    (Max Planck Institute for Astrophysics, Garching)
• Dark Matter: A Debate
• Hörsaal I, Physikalisches Institut

Abstract: The subject of this months Bethe Colloquium concerns a question at the interface of cosmology, astrophysics and elementary particle physics: the possible existence of Dark Matter. The existence of Dark Matter is the most prominent proposal to account for the discrepancy between measurements of the mass of galaxies, clusters of galaxies and the entire universe, and measurements based on the mass of the visible matter. So far the existence of Dark Matter is inferred from gravitational effects on visible matter and background radiation and not through direct detection. In his talk Professor S. White introduces the dark matter paradigm and explains its virtues. An alternative proposal to explain the observed discrepancies is introduced by Professor P. Kroupa. He argues that these effects could be due to a modification of the laws of gravity without the need of Dark Matter. The talks are followed by a discussion.

Update: The debate was recorded by uni-bonn.tv. You can find the podcasts, and some pictures of the event, here

October's Bethe Colloquium took place on 21. October (3:15 pm):

• Sergei Gukov    (CalTech, MPI for Mathematics, Bonn)
• A piece of 21st century mathematics that didn't make it into 20th century physics
• Lecture Hall MPI, Max Planck Institute for Mathematics

Abstract: This lecture will be about the physics of new knot invariants invented by Khovanov, Rozansky, Ozsvath, Szabo, Rasmussen, and other mathematicians circa 2000. The key ingredients of the proposed physical framework involve standard tools from gauge theory and string theory. It leads to a wealth of generalizations and comes with a few surprising features ...

From October 4 to October 8, 2010 the 2nd Bethe workshop will take place at the Physikzentrum Bad Honnef. This workshop is dedicated to the topic Cosmology meets Particle Physics. Please go to the workshop page for more information. The poster is avaliable for download here.

The workshop is jointly organized by

• Transregio 33 - The Dark Universe
  (Bonn, Heidelberg, Munich)
• SFB 676 - Particles, Strings and the Early Universe
  (Hamburg)

From August 23 to August 28, 2010 the 18th international conference on supersymmetry and unification of fundamental interactions SUSY 2010 will take place in Bonn.

Please go to the conference page for more information. The poster is avaliable for download here.

There was a Bethe Colloqium on 8. July (3:15 pm):

• Robbert Dijkgraaf    (University of Amsterdam)
• The unreasonable effectiveness of physics in mathematics
• Hörsaal I, Physikalisches Institut

Robbert Dijkgraaf is Distinguished University Professor of Mathematical Physics at the University of Amsterdam. From 1 May 2008 he is President of the Royal Netherlands Academy of Arts and Sciences. He was the recipient of the 2001 Physica Prize of the Dutch Physical Society and the 2003 NWO Spinoza Prize, the highest scientific award in the Netherlands.

Abstract: Understanding quantum fields and strings has not only involved beautiful geometric structures, it has also led to new powerful ideas that are transforming large parts of mathematics.

There was a Bethe Colloqium on 17. June (3:15 pm):

• Natan Andrei    (Rutgers University)
• Time evolution in quantum impurity systems
• Hörsaal I, Physikalisches Institut

Abstract: Quantum Impurity systems have traditionally provided a laboratory for studying theoretical and experimental aspects of the interplay between correlations and nonequilibrium dynamics. We shall present in this talk new approaches to the time evolution of some impurity models, studying in particular, their long time limit and its relation to thermalization.

There was a special Bethe String Seminar on 10. June (4:15 pm):

• Hirosi Ooguri    (CalTech and IPMU Tokyo)
• Wall crossing as seen by M theory and matrix models
• Conference Room I, Physikalisches Institut

Abstract: BPS counting problems are relevant to deep questions in quantum gravity, and they test our understanding of the superstring theory. In this talk, I will discuss these problems from a variety of perspectives ranging from M theory to dimer models, random walks and random matrix integrals.

There was a Bethe Colloqium on 20. May (3:15 pm):

• Dieter Lüst    (LMU and MPI Physik, München)
• Strings at the LHC?
• Hörsaal I, Physikalisches Institut

Abstract: The fundamental string scale, namely the typical mass to excite a vibrating string, is an unknown parameter in string theory. In case elementary particles can be identified with strings, and in case the string scale is as low as a few TeV, new spectacular stringy and new gravitational effects will be visible at the LHC. In this talk we discuss the production of TeV scale strings and some of the related stringy signatures at the LHC.

There was a Bethe Colloqium on 29. April (3:15 pm):

• Wilfried Buchmüller    (DESY, Hamburg)
• Quantum Leptogenesis
• Hörsaal I, Physikalisches Institut

From March 8 to March 11, 2010 the yearly workshop "Beyond the Standard Model" is taking place at the Physikzentrum Bad Honnef. This workshop is dedicated to research topics reaching from particle physics and cosmology to string theory. The deadline for registration is February 10, 2010. The topics and speakers of the pedagogical lectures are

• K. Choi (KAIST): Susy Breakdown and Mediation at the Time of the LHC
• F. Quevedo (Trieste): Recent Developments in String Phenomenology
• D. Schwarz (Bielefeld): Cosmic Microwave Background: Past, Present and Future
• A. Sen (Allahabad): String Theory and Black Hole Physics

The workshop is organized by Prof. A. Klemm from the Bethe Center.

There was a Bethe Colloqium on 21. Januar (3:15 pm):

• Matthias Neubert    (Universität Mainz)
• Effective field-theory tools for LHC physics
• Hörsaal I, Physikalisches Institut
• Slides as PDF File