Past activities

On December 14 the Bonn-Cologne Number Theory and Physics Meeting took place at the Bethe Center for Theoretical Physics.  It was organized by Kathrin Bringmann, Ben Kane, Albrecht Klemm, Jan Manschot, Don Zagier and Sander Zwegers.
The intention of the meeting was to bring together theoretical physicists and mathematicians working on the overlap of number theory and  theoretical physics.

Confirmed speakers included Thomas Creutzig (Darmstadt), Martin Möller (Frankfurt) and Tobias Mühlenbruch (Hagen). The schedule can be found here.

December's Bethe Colloquium took place on December 06 (3:15 pm) in Hörsaal I:

• Rocky Kolb (University of Chicago)
• Dark Matter Universe: On the Threshold of Discovery
• Hörsaal I, Physikalisches Institut

Abstract: Astronomical evidence, accumulated over eight decades, implies that most of the mass of the present universe is in the form of a new type of matter, referred to as "dark matter."  The most promising explanation for dark matter is that it is in the form of a new species of elementary particle: a weakly interacting massive particle, or WIMP.   In the lecture I will present the status of the WIMP conjecture and propose that we are on the threshold of testing the WIMP hypothesis.

November's Bethe Colloquium took place on November 15 (3:15 pm) in Hörsaal I:

• Ulrich Ellwanger (Université Paris-Sud)
• The Higgs Boson
• Hörsaal I, Physikalisches Institut

Abstract: First, the reason for the existence of a Higgs boson will be explained in simple terms. Its production mechanisms and detection methods at particle accelerators will be reviewed, and confronted with recent results at the Large Hadron Collider. Finally I discuss what we can learn from precision measurements of the properties of the Higgs boson.

The Bethe Forum on Unification and String Theory is a three week program focusing on

• Global Model Building with a bias towards the Heterotic String
• Local Model Building focusing on constructions in the context of type IIB/F-theory

The workshop took place from September 24th to October 12th. In the second week, there was the 4th Bethe Center workshop on Unification and String Theory at the Physikzentrum Bad Honnef. The rest of the workshop was held at the bctp.
The homepage of the program can be found here.

The school (20-22 August) presented in great depth the most important ingredients for the global interpretation of LHC and other data, especially in the light of searches for supersymmetry. Topics covered were limit setting and fitting, profile likelihood technique with tutorial, ROOTSTATS and worksspaces, MVA methods, inclusive and model-independent SUSY searches and their interpretation. Talks on physics topics such as Higgs physics, BS-->mumu or astrophyical input quantities complemented the programme. A highlight lecture on global fits in the past and in the future built the bridge to the workshop part (23 August) to which also the school participants are heartily invited.
The homepage of the program can be found here.

String and gauge theories in various dimensions and their duality relations have been a constant source of inspiration for mathematics over the last decades. Conjectures have been converted into theorems that underlie emerging mathematical fields. Application of new mathematical structures on the other hand is essential to understand the nature of string theory. String-Math is the annual conference that was founded to reflect the most significant progress at the interface of string theory and mathematics. The homepage of the conference is available here.

The Bethe-Forum "Lecture Series on Mathematical String Theory", which took place from July 2nd to July 13th, was a school on recent topics in Mathematical String Theory. It was intended as a preparation to the String-Math 2012 Conference for graduate students and researchers alike. The aim was to introduce current research topics in the field to both mathematicians and theoretical physicists and to bring together the respective physics and mathematics communities.
The homepage of the program can be found here.

June's Bethe Colloquium took place on June 28 (3:15 pm) in Hörsaal I:

• Erik Verlinde (University of Amsterdam)
• Dark Matter, Dark Energy and the Emergence of Gravity
• Hörsaal I, Physikalisches Institut

Abstract: Insights from black hole physics and string theory strongly suggest that gravity is an emergent phenomenon and can be derived from an underlying microscopic description. The analogy between the gravitational field equations near black holes and thermodynamics and the known gauge/gravity dualities in string theory give particularly important clues towards the microscopic mechanism behind the emergence of gravity. Motivated by these ideas and by our best current understanding of M-theory, I propose a microscopic framework that naturally explains the origin of gravity, without presuming its presence. In this framework gravity, or rather inertia, arises as an adiabatic reaction force caused by fact that the microscopic phase space volume is influenced by the positions of matter. In a cosmological setting we find that that these ideas naturally give rise to the presence of dark energy, and furthermore lead to a quantitative match with the observed phenomena associated with dark matter, such as the flattening of rotation curves in spiral galaxies.

May's Bethe Colloquium took place on May 24 (3:15 pm) in Hörsaal I:

• Michael Duff (Imperial College London)
• Black holes and qubits
• Hörsaal I, Physikalisches Institut

Abstract: Two different branches of theoretical physics, string theory and quantum information theory (QIT), share many of the same features, allowing knowledge on one side to provide new insights on the other. In particular the matching of the classification of stringy black holes and the classification of four-qubit entanglement provides a falsifiable prediction in the field of QIT.

On Thursday, April 26 German schools celebrated Girls' Day, an event intended to promote scientific, technical, IT and trade professions among female high school students. The gymnasium student Clara Feinhals visited the Bethe Center that morning. There she talked with the PhD student Nana Cabo Bizet about particle physics, formulating many questions. She learned about fundamental natural forces and the goal to understand gravity together with quantum mechanics, e.g. with string theory and extra dimensions. She also got to know about the LHC experiments at CERN, and what scientists are searching there. At the end of the visit they both discussed about the physics lessons Clara takes now at school on magnetism, lenses, heat and states of matter. They also talked about potential issues in mostly male dominated professions, and how women can try to overcome them. Clara also talked to some other physicists in our center, among them the visitor Martin Savage and PhD student Encieh Erfani. We think the visit gave her a general idea on theoretical particle physicists' work.

In the last years, the simple quark model picture of hadrons has been severely put into question by a cornucopia of experiments that show signals of so-called "exotic hadrons". At present, the nature of these states is not understood. The aim of this program is to sharpen the theoretical approaches to describe these states and pin down pertinent experimental signatures to differentiate between various options. Key issues of this program are:

• Charmonia and exotica (decays, transitions, ...)
• Theory of multiquark states
• Theory of hadronic molecules
• Hadron resonances in Lattice QCD

The homepage of the program can be found here
.

April's Bethe Colloquium took place on April 12 (3:15 pm) in Hörsaal I:

• Carsten Andrew Lütken (University of Oslo)
• Escher-symmetries discovered in Nature?
• Hörsaal I, Physikalisches Institut

Abstract: Two decades ago Graham Ross (Oxford University) and the speaker proposed that all universal data in quantum Hall systems is encoded in a family of emergent modular symmetries of the low energy effective field theory. This bold conjecture is reviewed, and shown to be in excellent agreement with a new generation of experiments. These are so cold that thermal fluctuations appear to be swamped by quantum fluctuations, rendering the emergent symmetry essentially exact. The symmetry predicts quantization of the transport coefficients, as well as the location of all quantum critical points, at certain rational points in the conductivity plane. The best experiments to date agree at the per trillion level for the Hall quantization, and at the per mille level for critical points.

Kyriakos Papadodimas continues discussions with participants of the Bethe Forum Lecture Series on Holography and Physics at Strong Coupling in the BCTP hallway.

Another Bethe Forum program took place from March 19 to 23. The lecture series was intended for graduate and post-graduate students. The topics that were covered include

• From Large N Gauge Theories to Strings
• Basics of the AdS/CFT Correspondence
• Applications to Strongly Coupled Field Theories
• Lessons for Quantum Gravity, Black Holes and Cosmology

The homepage of the program can be found here.

From March 12 to March 15, 2012 the yearly workshop "Beyond the Standard Model" will took place at the Physikzentrum Bad Honnef. The workshop focused on recent developments in the theory of fundamental particles, the physics of the early universe, and mathematical physics. There was a 90-minute introductory pedagogical lecture each morning, followed by shorter talks by the participants.

The topics and speakers of the pedagogical lectures were:

• E. Dudas (Paris): Non-linear supersymmetry
• M. Krämer (Aachen): Implications of early LHC data for phenomenology
• G. Servant (CERN): The cosmo-particle connection
• J. Teschner (Hamburg): News on 4d SYM

From March 05 to 10, there was a Bethe Forum event: The workshop on the AGT Conjecture, organised by Rainald Flume and Albrecht Klemm.

The workshop′s intention was to bring together experts in two-dimensional conformal field theory and four-dimensional supersymmetric Yang-Mills theories to discuss the overlap of the two fields as suggested by AGT.

The homepage of the program can be found here.

On January 19, the chancellor of the University, Dr. Reinhard Lutz, visited the new rooms of the Bethe Center, which the University significantly helped to fund. The picture shows him with bctp Director Hans Peter Nilles in one of the discussion areas on the corridor.

In the week from January 16 to 20, the bctp had three visitors working on particle phenomenology. In the pictrue, you can see Ben O'Leary and Eliel Camargo from Würzburg and Sho Iwamoto from Tokyo (third, fourth and sixth from the left) with Jamie Tattersall, Daniel Schmeier, Florian Staub and Kilian Nickel from the group of Professor Dreiner in one of the discussion areas.

On January 12th and 13th the bctp hosted a meeting of the European Twisted Mass Collaboration (ETMC). The meeting was focused on discussing and developing a software suite for simulations in lattice quantum chrmonodynamics. The meeting had local and European participants, for instance from the Netherlands, Switzerland and Spain.

Saúl Ramos-Sánchez from the National University of Mexico (UNAM) visited the Bethe Center in January 2012. He received his Ph.D. in the group of Prof. Nilles in Bonn. His research interests focus on grand unified theories, supersymmetric models, supergravity and string theory.

Humboldt research prize laureate Professor Jihn E. Kim from Seoul National University visited the Bethe Center from December 2011 to February 2012. He is a member of the Bethe Center advisory board and a frequent visitor to Bonn. Prof. Kim and Prof. Nilles enjoy a close collaboration for almost 30 years. Prof. Kim's research interests concentrate on particle physics and cosmology.

January's Bethe Colloquium took place on January 12 (3:15 pm) in Hörsaal I:

• Harald Fritzsch (LMU Munich)
• From Quarks to Chromodynamics
• Hörsaal I, Physikalisches Institut

Abstract: Today QCD is regarded as the correct theory of the strong interactions. In 1971 Gell-Mann and I introduced the color quantum number of the quarks, one year later the exact color symmetry group was interpreted as the gauge group of QCD. The self-coupling of the gluons leads to the property of asymptotic freedom and to the confinement of the quarks and gluons. The proton mass can be calculated, but the quark masses are free parameters. The quarks and gluons have been observed at high energies as hadronic jets.