Topic: 
Measuring intact protons at the LHC: From the odderon discovery to the search for axionlike particles 
Date: 
21.06.21 
Time: 
16:15 
Place: 
cyberspace 
Guest: 

University of Kansas 

Abstract: 
In the first part of the talk, we will describe the odderon discovery by the TOTEM and D0 experiments. The analysis compares the p pbar elastic cross section as measured by the D0 Collaboration at a centerofmass energy of 1.96 TeV to that in pp collisions as measured by the TOTEM Collaboration at 2.76, 7, 8, and 13 TeV. The two data sets disagree at the 3.4 sigma level and thus provide evidence for the tchannel exchange of a colorless, Codd gluonic compound, also known as the odderon. We combine these results with a TOTEM analysis of the same Codd exchange based on the total cross section and the ratio of the real to imaginary parts of the forward elastic strong interaction scattering amplitude in pp scattering, leading to a combined significance larger than 5 sigma. In a second part of the talk, we will describe the perspective on the search for quartic anomalous couplings and axionlike particles using tagged protons in the final state, leading to sensitivities to beyond standard model physics that improve by 2 to 3 orders of magnitude on the coupling. We will finish by decribing briefly the ultra fast silicon detectors for timing measurements as well as for medical and cosmic ray physics applications. 
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Topic: 
Random matrices, spin glasses, and machine learning 
Date: 
23.07.21 
Time: 
16:15 
Place: 
ZOOM/Konferenzschaltung 
Guest: 

Oxford University 

Abstract: 
I will describe some problems relating to machine learning and their connections to random matrix theory and spin glasses. These connections give a mathematical framework for understanding in qualitative terms the effectiveness of certain algorithms that are important in machine learning, but developing them into precise models remains a major challenge. I will reflect on the different roles played by models in computer science and physics, focussing on those involving random matrices. 
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Topic: 
Machine Learning for Thermodynamic Observables in Lattice Field Theories 
Date: 
06.07.21 
Time: 
14:15 
Place: 
Online, via ZOOM 
Guest: 

Perimeter Institute, Ontario, Canada 

Abstract: 
In this talk, I will discuss how applying machine learning techniques to lattice field theory is a promising route for solving problems where Markov Chain Monte Carlo (MCMC) methods are problematic. More specifically, I will show that deep generative models can be used to estimate thermodynamic observables like the free energy, which contrasts with existing MCMCbased methods that are limited to only estimate free energy differences. I will demonstrate the effectiveness of the proposed method for twodimensional $\phi^4$ theory and compare it to MCMCbased methods in detailed numerical experiments. 
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Topic: 
Der Groveralgorithmus auf einem universellen Quantencomputer  Nur eine Simulation oder tatsächlich umsetzbar? 
Date: 
20.07.21 
Time: 
10:15 
Place: 
ZOOM / Konferenzschaltung 
Guest: 

Universität Bielefeld 

Abstract: 

Contact person: 
Topic: 
The Character Expansion in effective Theories for chiral Symmetry Breaking 
Date: 
03.12.20 
Time: 
16:30 
Place: 
ZOOM / Konferenzschaltung 
Guest: 

Universität Bielefeld 

Abstract: 

Contact person: 
Topic: 
Schur expansion of randommatrix reproducing kernels 
Date: 
21.07.21 
Time: 
09:00 
Place: 
ZOOM / Konferenzschaltung 
Guest: 

Universidade de Lisboa 

Abstract: 
We explain how to obtain expansions of reproducing kernels of the ChristoffelDarboux type in terms of Schur polynomials. The method is simply based on evaluations of averages of characteristic polynomials and Schur polynomials in random matrix ensembles. We explicitly compute some new Schur average and the ensuing expansion of the random matrix kernel. In addition to classical and qdeformed cases on the real line, we use extensions of DotsenkoFateev integrals to obtain expressions for kernels on the complex plane. We will comment also on a known interplay between Wronskians of Laguerre polynomials, Painlevé tau functions and conformal block expansions, now viewed in relation to the Schur expansion discussed. 
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