Announcements

May's Bethe Colloquium will take 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) visits 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 visits 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.

The Bethe Center wishes merry christmas and a happy new year. As you can see on the picture, Santa Claus (center, seated) visited the new bctp Seminar Rooms for a special presentation.

December's Bethe Colloquium took place on December 08 (3:15 pm) in Hörsaal I:

• Manfred Lindner (MPIK Heidelberg)
• Neutrinos as Probes of new Physics
• Hörsaal I, Physikalisches Institut

Abstract: Neutrino physics is in an exciting phase of dicovery which has given us very valuable results already. As rather special objects, neutrinos on the one hand allow important and unique insights into the fundamental properties of particle physics. One the other hand, they can be used as probes for a variety of sources, which gives interesting connections to current topics in astrophysics, cosmology, nuclear physics and geophysics. In the talk we will review the current state of the field and discuss recent results.

On December 7-9, the 5th Annual Meeting of the Helmholtz-Alliance "Physics at the Terascale" will take place in Bonn, Beethovenhalle Forum Süd. The three-day meeting will bring together more than 250 German particle physicists from theory and experiment to discuss recent results from the LHC as well as progress on future Linear Colliders and on detector development and grid computing. The programme is available here.

The Helmholtz Alliance "Physics at the Terascale" bundles German activities in the field of high-energy collider physics. It is a network comprising all German research institutes working on LHC experiments, a future linear collider or the related phenomenology - 18 universities, two Helmholtz Centres and one Max Planck Institute. The Alliance includes the following topics: development of new accelerator and detector technologies, methods of data analysis, development of theoretical models and methods and development of the relevant computing infrastructure.

From October 19, the groups working on particle physics and string theory moved into the new bctp corridor on the top floor of the building Wegelerstraße 10. The new rooms include offices for students and postdocs and space for visitors (e.g. during the Bethe Forum) as well as seminar rooms. At the same time, the condensed matter theory groups have moved from the AVZ to the first floor of the PI.

From November 2nd to November 18th, there will be the inaugural program of the Bethe Forum. Topics covered will be

• LHC and Collider Phenomenology
• Dark Matter
• Grand Unification

During the three weeks, experts will meet and discuss current topics in the above mentioned areas of physics. More information can be found on the program's homepage.

October's Bethe Colloquium took place on October 13 (3:15 pm):

• François Englert (Université Libre, Brussels)
• Broken Symmetry
• Hörsaal I, Physikalisches Institut

François Englert is one of the pioneers of spontaneous symmetry breaking in quantum field theory. The Brout–Englert–Higgs mechanism, suggested in 1964, proved to be the key to understand the masses of the W and Z bosons and opened the way to the unification of weak and electromagenetic interactions in the Standard Model. In this talk, Professor Englert will give a general discussion of broken symmetry, from its origin in phase transitions to its use in Yang–Mills theory, with particular emphasis on conceptual issues.

June's Bethe Colloquium took place on June 30 (3:15 pm):

• Volker Schomerus (DESY)
• Of Mesons and Metals - Bethe and the 5th Dimension
• Hörsaal I, Physikalisches Institut

Abstract: Quantum field theory is highly successful in explaining features of our world, yet still physicists often struggle to extract well-known phenomena such as e.g. observed meson resonances in particle physics, etc. Over the last decade, an intriguing geometric reformulation of 4-dimensional quantum systems has begun to emerge which involves strings in certain 5-dimensional curved backgrounds. The relevant concepts and methods of string geometry offer a powerful new approach to quantum physics. Remarkably, the foundations of classical string geometry were laid nearly a century ago; they may be traced back in particular to Hans Bethe's work on the theory of metals.

Podcast: The colloquium has been recorded by uni-bonn.tv – you can find the video here (see also the list of bctp podcasts).

The annual conference PLANCK2011 "From the Planck Scale to the ElectroWeak Scale" is a joint enterprise of several European research groups in the framework of the Marie Curie ITN network "UNILHC". This year the PLANCK meeting was organized by the Lisbon node. On Thursday June 2nd the programme was dedicated to "PeterFest" in honour of Hans Peter Nilles. Some photos of the event can be found here.

The Hoyle state is an excited state of the carbon-12 nucleus which is crucial for the production of carbon and heavier elements in stars via fusion of three helium nuclei (see picture). For this reason it was predicted to exist by Fred Hoyle in 1954, and discovered experimentally shortly afterwards. However, a theoretical derivation of the state and its properties was lacking so far. In a recent paper (PRL or arXiv), Ulf Meißner, associate director of the bctp, and collaborators from the universities of Bochum and North Carolina have presented a calculation of the Hoyle state from first principles using a combination of lattice simulations and chiral effective field theory. The results agree well with experimental data and open up the path to thoroughly investigating the physics of this important state of the carbon nucleus.

May's Bethe Colloquium took place on May 26 (3:15 pm):

• Gia Dvali (LMU Munich and CERN)
• Microphysics and Nature's Fundamental Length
• Hörsaal I, Physikalisches Institut

Abstract: We review an emerging underlying connection between microphysics and the fundamental shortest length-scale of nature. We discuss how the latter length is determined by seemingly unrelated properties of long-distance particle physics, such as number and symmetries of elementary particles. We review some phenomenological implications of this connection, such as physics of micro black holes that should be accessible whenever the fundamental length can be probed in collider experiments. We discuss how the existence of the minimal length sheds a very different light at the concept of ultra-violet completion, according to which, at very high energies physics of elementary particles becomes governed by classical dynamics.

Humboldt prize laureate Prof. Howard Haber from the University of California, Santa Cruz, is spending his research visit at the Bethe Center as a guest of BCTP members Prof. Manuel Drees and Prof. Herbert Dreiner. The picture shows the president of the Humboldt foundation, Prof. Schwarz (left), who is presenting Prof. Haber (right) with the Humboldt prize during the ceremony at the annual Symposium for Research Awardees in Bamberg, on March 26th, 2011.