Announcements

• Bethe-Colloquium by Corinna Kollath (Bonn), June 6th, 2019
• Bethe-Colloquium by Yuval Grossman (Cornell University, LEPP), July 4th, 2019
• Bethe Forum "Number Theoretic Methods in Quantum Physics", July 15th - 19th, 2019
  Organizers: H. Jockers (PI Bonn, bctp), A. Klemm (PI Bonn, bctp), H. Monien (PI Bonn, bctp), G. Oberdieck (HIM Bonn) and D. Zagier (MPIfM, Bonn)
• Bethe Forum "Multihadron Dynamics in a Box", Sept. 9th - 13th, 2019
  Organizers: M. Mai (Washington, DC), U.-G. Meißner (Bonn / Jülich), A. Rusetsky and C. Urbach (both Bonn)
• Lecture Series "Machine Learning and its Applications" by Fabian Ruehle (CERN), Oct. 7th - 10th, 2019

Further information will be given as soon as it is available.

The next Bethe Colloquium will take place on Thursday, June 6th, 2019, at 4:15 pm in Hörsaal I.

• Corinna Kollath (HISKP, Bonn)
• Unconventional dynamics of ultracool bosons in optical lattices
• Hörsaal I, Physikalisches Institut

Abstract: Atomic gases cooled to Nanokelvin temperatures are a new exciting tool to study a broad range of quantum phenomena. In particular, an outstanding degree of control over the fundamental parameters, such as interaction strength, spin composition, or dimensionality has been achieved. This has facilitated access to strongly correlated quantum many body physics in exceptionally clean samples. For example, artificial periodic structures for the atomic gas can be created using laser light to mimic condensed matter systems. Further, the outstanding tunability of cold gases allows to rapidly change the system parameters or to induce a coupling to an environment and to observe the subsequent quantum evolution. This ability poses new challenges for the understanding of quantum dynamics in correlated many-body systems. I will report on recent progress on investigating bosonic gases in optical lattices coupled to dissipative light fields described by Markovian Master equations. In particular, we point out different dynamical regimes: The first one is an algebraic decay of correlations which is followed by a stretched exponential decay. We analyze the origin of this unconventional dynamics. The algebraic behavior is related to the continuum spectrum of the bosonic gas and we develop a classical diffusion equation description for the dynamics. In contrast, the stretched exponential dynamics can be traced back to the existence of rare states with increasingly long time scales.

As a major outcome of the work on nuclear lattice effective field theory in the DFG-funded project CRC 110 "Symmetries and the emergence of Structure in QCD", a monograph was just published by Timo A. Lähde (associated scientist) and by Ulf-G. Meißner in the Springer Lecture Notes in Physics Series as volume 957 (May 2019).

We are happy to announce the Bethe Forum on "Number Theoretic Methods in Quantum Physics", July 15th to 139h, in the Bethe Center for Theoretical Physics in Bonn. The Forum is organized by H. Jockers (PI Bonn, bctp), A. Klemm (PI Bonn, bctp), H. Monien (PI Bonn, bctp), G. Oberdieck (HIM Bonn) and D. Zagier (MPIfM, Bonn).

For more information as well as the registration form please see the event webpage.

From September 9 - 13, 2019, the Bethe Forum "Multihadron Dynamics in a Box" will take place in the Bethe Center for Theoretical Physics in Bonn. The Forum is organized by M. Mai (Washington, DC), U.-G. Meißner (Bonn / Jülich), A. Rusetsky and C. Urbach (both Bonn).

For more information as well as the registration form please see the event webpage.

Recent years have witnessed a growing interest in the study of three-particle systems in lattice QCD. Substantial progress has been achieved both in the development of the methods that enable one to extract infinite-volume observables from lattice data produced on finite-size lattices, as well as in Monte-Carlo calculations of the three-particle systems, but important recent developments in the two-particle sector will also be addressed, since these questions are inherently related to each other.
In particular, it is planned to discuss the following questions:

• What is the best strategy in the analysis of data in the three-particle sector?
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• What are the quantities to extract form the finite-volume sector?
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• How the further progress in the field looks like after the derivation of the quantization condition (analysis of the data on the Roper resonance, three-particle decay matrix elements, etc.)?
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• What are the present status and immediate perspectives of lattice simulations in the three-particle sector? For example, can one expect the calculation of the excited levels in the three-particle sector? Are the calculations in many-body (four and more) systems feasible in a forseeable future?

Fabian Ruehle (CERN, Geneva) will give a Lecture Series on "Machine Learning and its Applications" from October 3 - 11, 2019, in the Bethe Center for Theoretical Physics in Bonn.

Abstract: Machine Learning techniques, in particular neural networks, have become an integral part of our lives. Due to their versatile nature, they are applied in the private and academic sector with tremendous success. In these lectures, I will first review the basic building blocks of neural networks and how they are trained. I will then discuss popular neural network architectues and how they are used in unsupervised, semi-supervised and supervises machine learning. I will also intrudce other common machine learning techniques and present example applications to problems in Physics (ranging from Astrophysics and Cosmology to Particle Physics, Mathematical Physics and String Theory). In the exercises, I will use the techniques introduced in the lectures to solve simple problems in real time.

For more information please check the event webpage.