Announcements

July's Bethe Colloquium will take place on July 4 (3:15 pm) in Hörsaal I:

• Katrin Wendland (Freiburg University)
• Moonshine in Mathematics and String Theory
• Hörsaal I, Physikalisches Institut

Abstract: The story of "monstrous moonshine" is a famous success story of mutual interactions between mathematics and physics. In mathematics, Conway/Norton's "monstrous moonshine conjecture" relates a sporadic group, commonly known as the Monster, to "modular" functions on the upper complex half plane. In physics, the Monster occured first as the automorphism group of a certain conformal quantum field theory (CFT), let us call it the Monster CFT. Richard Borcherds used the latter to prove the former and was awarded a Fields Medal for his proof of "monstrous moonshine" in 1989. Recently, Eguchi, Ooguri and Tachikawa have observed a phenomenon in a certain class of CFTs which is reminiscent of monstrous moonshine, where the role of the Monster is taken by another sporadic group, the Mathieu group M24.

While axiomatic approaches to CFT are tedious, such that a detailed description of any CFT would go beyond the scope of this talk, CFTs arise naturally in string theory, and in the particular case of the Monster CFT much of its construction can be motivated by simple geometry. This is the approach taken in this talk, aiming to give an overview on some geometric aspects of moonshine, including - if time permits - a view on Mathieu moonshine.

June's Bethe Colloquium took place on Thursday, June 13 (3:15 pm) in Hörsaal I:

• Laura Covi (University Göttingen)
• Supergravity, Dark Matter and the LHC
• Hörsaal I, Physikalisches Institut

Abstract: Symmetries have been fundamental in driving progress in theoretical physics and are at the basis of many extensions of the Standard Model of particle physics. In this talk, I will discuss in particular models of local supersymmetry, also called supergravity. Supergravity extendes the Poincare` algebra with fermionic generators and predicts the existence of superpartners with different spin for all the SM particles including also the graviton. I will review the consequences of supergravity for cosmology and Dark Matter and confront the models with the recent LHC searches for new particles.

There were two Bethe Forum Programs accompanying the Planck 2013 conference hosted at Bonn University. The programs took place in the week before and after the conference. The Bethe Forum in the week before Plack 2013 from May 13th to May 17th carried the title "Planck and the Early Universe", and the Bethe Forum after Plack 2013 from May 27h to May 31st had the title "Supersymmetry: Tools meet Models". More information is available here.

The annual conference "Planck 2013 - From the Planck Scale to the Electroweak scale" took place from May 20th to May 24th at Bonn University. It is a joint enterprise of several European research groups in the framework of the Marie Curie ITN network "UNILHC". There were two Bethe Formum programs in the week before and after the conference accompanying the program. The conference homepage can be found here.

On May 14 the Bonn-Cologne Number Theory and Physics Meeting took place at the MPI Lecture Hall, MPIM - Bonn, Vivatsgasse 7. 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.

The speakers were Francis Brown (Paris), Sameer Murthy (Amsterdam), Gunther Cornelissen (Utrecht) and Tamás Hausel (Lausanne). The schedule can be found here.

May's Bethe Colloquium took place on Monday, May 6 (2:15 pm) in Seminar Room I (We 2.019, note unusual date and time):

• Qimiao Si (Rice University)
• Quantum Criticality and Strongly Correlated Fermions
• Seminar Room I (2.019), BCTP, Wegelerstr. 10

Abstract: Quantum criticality describes the collective fluctuations of matter undergoing a continuous phase transition at absolute zero. It is of extensive current interest to a variety of quantum condensed matter systems, in which competing orders frequently occur. It is also being discussed in other systems, including in holographic settings.
In this talk, I will summarize the basic concepts of quantum criticality, developed within the framework of Landau theory of critical phenomena. I will then discuss the topical issues concerning “beyond-Landau” quantum critical points, and their implications for the physics of strongly correlated fermion systems. Finally, I will consider the connections – both the similarities and differences -- of the latter with the quantum critical behavior in holographic models of non-Fermi liquids.

April's second Bethe Colloquium took place on April 25 (3:15 pm) in Hörsaal I:

• Ulf-G. Meißner (Bonn University)
• The Hoyle state and the fate of carbon-based life
• Hörsaal I, Physikalisches Institut

Abstract: The Hoyle state has been an enigma to nuclear theory for half a century. I present the first ab initio calculation of this elusive excited state in the spectrum of carbon-12 and discuss its structure. Simulated worlds with different quark mass and fine structure constants are also considered and the role of the Hoyle state in our anthropic view of the universe is elucidated.

April's first Bethe Colloquium took place on April 18 (3:15 pm) in Hörsaal I:

• Fabian Essler (Oxford University)
• Quantum Quenches in one dimensional many-particle systems
• Hörsaal I, Physikalisches Institut

Abstract: I consider the non equilibrium time evolution after a "quantum quench": an isolated many-particle system is initially prepared in its ground state and at time t=0 a parameter such as a magnetic field or an interaction strength is changed suddenly. I discuss realisations of such protocols in systems of ultra-cold trapped atoms and review general expectations regarding the late-time behaviour of these systems. Interestingly, in the thermodynamic limit the expectation values of local observables relax to time-independent values, even though the system is not coupled to a bath. I show that conservation laws affect the non equilibrium dynamics and the stationary behaviour very strongly and present detailed results for the "Ising model" of quantum quenches, the transverse-field Ising chain.

The moment has come! On March 21st, the Planck satellite will release its first cosmological results. This lecture series will put this exciting event into context. After a quick review of basic cosmology and the physics of the cosmic microwave background, the lectures will present a modern view on the physics of inflation. This will include some old classics (such as the quantum computation of the primordial density fluctuations) as well as more recent insights (such as the application of methods from effective field theory and string theory to inflation). Broadly speaking, the goal of the lectures is to explain what we can hope to learn about primordial cosmology and particle physics from the observations of the Planck satellite. The lectures should be accessible to both particle physicists and cosmologists.

The homepage of the program is available here.

Humbolt prize laureate Professor Martin Savage visits the BCTP and the HISKP from January to March. He is a renowned theorist in the field of strong interaction physics (QCD). He is one of the pioneers to apply effective field theories to nuclear physics. He also is leading the attempts of ab initio calculations of few-hadron systems and atomice nuclei using lattice QCD. These efforts have led to some of the most precise calculations made in this very difficult field. In Germany, Martin Savage continues to work on these topics and will try to perform a high-precision calculation of nucleon-nucleon scattering for close-to physical quark masses.

January's Bethe Colloquium took place on January 14 (3:15 pm) in Hörsaal I:

• Subir Sachdev (Harvard University)
• Entanglement, holography and the quantum phases of matter
• Hörsaal I, Physikalisches Institut

Abstract: Electrons in many interesting materials, such as the high temperature superconductors, form states with complex varieties of quantum entanglement. I will present a broad classification of quantum many-particle states with long-range entanglement, and describe recent theoretical progress in characterizing them. The methods of holography, drawn from string theory, have given us a new tool to describe such states, by relating them to theories of gravitation in curved spacetimes with an extra dimension. I will discuss the impact of such ideas on studies of quantum phase transitions, and of novel metals.

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.

The confirmed speakers were Thomas Creutzig (Darmstadt), Stefan Hohenegger (MPI), Martin Möller(Frankfurt) and Tobias Mühlenbruch (Hagen). The schedule can be found here.

December's Bethe Colloquium will take 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 takes place from September 24th to October 12th. In the second week, there will be the 4th Bethe Center workshop on Unification and String Theory at the Physikzentrum Bad Honnef. The rest of the workshop will be 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", taking place right now (from July 2nd to July 13th), is a school on recent topics in Mathematical String Theory. It is intended as a preparation to the String-Math 2012 Conference for graduate students and researchers alike. The aim is 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) 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.