Theoretische Physik II

RTG seminar series summer 2024 @ TP2


It´s a pleasure to invite you to the special lectures on "Machine Learning and Artificial Intelligence for BSM Physics" by Dr. Miguel Crispim Romão, IPPP Durham.

15. May 2024 - SE 22.02.008 - 10:15 a.m. and
16. May 2024 - SE 22.02.008 - 9:15 a.m.

Dr. Miguel Crispim Romão, IPPP Durham
Title: Machine Learning and Artificial Intelligence for BSM Physics

In this short course catered to BSM phenomenologists and theorists, I will introduce the main concepts behind Machine Learning (ML) and Artificial Intelligence (AI) and apply them to BSM physics. The first lecture focuses on basics of ML, covering different types of learning, models, and introducing proper ML workflow methodologies. The second lecture introduces evolutionary computing, an area of AI often overlooked in the ML literature, and showcases the application of ML/AI to explore highly constrained multidimensional BSM parameter spaces. Both lectures will be accompanied by practical code examples/exercises.

25. April 2024 - SE 22.00.017 - 5:15 p.m.

MSc. Rosy Caliri
Title: Electroweak spin-1 resonances in composite Higgs models

Composite Higgs theories incorporating partial compositeness are gauge theories, wherein the Higgs boson emerges as a pseudo-Nambu-Goldstone boson (pNGB), while top-partners manifest as bound states of three hyperfermions coming from a UV completion. These models predict additional pNGBs and spin-1 resonances, which are potentially observable at the LHC. Specifically, we focus our attention on the exploration of the SU^2 (4) /SU (4) symmetry breaking pattern.

RTG seminar series winter 2023/2024 @ TP2

25. January 2024 - SE 22.00.017 - 5:15 p.m.

MSc. Aryan Borkar
Title: Probing strange particle production in ATLAS experiment

The master thesis study aims to assess the production of φ(1020) mesons in inelastic scattering of protons (pp collision) using data collected by the ATLAS experiment at the Large Hadron Collider (LHC) at the centre-of-mass energy √s = 13.6 TeV. The findings may be crucial in creating phenomenological soft hadroproduction models to enhance total inelastic pp cross-section predictions as well as in comprehending physics processes at high energies with small momentum transfers ( ∼1 GeV). The end part of the talk also focuses on the prospective PhD work based on studying electroweak symmetry breaking mechanism by probing electroweak vector boson scattering (VBS) processes that occur in proton-proton collisions at the LHC.

21. December 2023 - SE 22.00.017 - 5:15 p.m.

MSc. Jonathan Karl
Title: The AdS/CFT correspondence and holography in discrete spacetime

The AdS/CFT correspondence is one of the most remarkable discoveries in theoretical physics of the last 25 years. It has fundamentally changed the way physicists view gravity, as well as providing tools to study strongly coupled quantum systems. In this talk, I will present Maldacena's original derivation of the correspondence, which is based on a duality between open and closed strings, in the presence of D3-branes. Furthermore, I will present a generalization of the correspondence to discrete spacetime. I consider aperiodic spin chains, as possible boundary theories in the discrete setup. Finally, I propose a discrete analogue of JT gravity, defined on a hyperbolic lattice as a dual bulk theory.

23. November 2023 - SE 22.00.017 - 5:15 p.m.

MSc. Deepali Singh

The seminar will take place in the summer semester 2024.

26. October 2023 - SE 22.00.017 - 5:15 p.m.

MSc. Yang Liu
Title: Holographic flavor symmetry breaking: from QCD to composite Higgs

As is known that holographic models can produce the QCD meson spectrum. Yet these models assume the flavor symmetry to be conserved, some of the states are thus degenerated. In the first part of this talk, I will show how to break the flavor symmetry in a holographic model in the QCD to get the full meson spectrum. In the second part, we extend this method to a minimal composite Higgs model, the SU(4)/Sp(4)→ SU(2)*SU(2), where the second breaking is implemented by an NJL type of interaction.

RTG seminar series summer 2023 @ TP2

18. July 2023 - SE 31.00.017 - 4:30 p.m.

MSc. Christoph Haitz
Title: NLO QCD predictions for polarised ZW$^+$ production with semileptonic decay

With the help of the pole approximation, observables with polarised intermediate resonances can be calculated. Gauge-boson-pair production represents a particularly interesting class of processes to study polarisation. The definition of polarised signals at amplitudue level has enabled successful phenomenological studies of leptonically decaying vector bosons. The natural step forward from this is the investigation of bosons decaying into hadrons. In this talk I discuss the NLO QCD predictions for the production of a polarised ZW$^+$ pair, where the W$^+$ boson decays hadronically and the Z boson leptonically. Of particular interest are observables that are well suited for the discrimination amongst different polarisation states of both weak bosons. In addition I analyse the significant impact of NLO QCD corrections on differential distributions.

20. June 2023 - SE 31.00.017 - 4:30 p.m.

MSc. Lucas Klein
Title: Cross-section measurement of top quark pair with additional b-jets at ATLAS

The top quark pairs with additional b-jets provide very interesting tests of QCD at higher orders. It also represents an important background to the SM processes directly probing the coupling of the Higgs boson with the top quark. I will highlight the cross-section measurements of this process in the dilepton final state using the data collected with the ATLAS detector. The dilepton final state provides very clean signature with some ambiguity of jets produced from the decay of the top quark and from the extra QCD radiation. My talk will also highlight the estimation of top-quark pair background in the signal events where either an additional c-jet or a light-flavour jet is mistagged.  

23. May 2023 - SE 31.00.017 - 4:30 p.m.

MSc. Manuel Kunkel
Title: Uncovering BSM scalars with neural networks

We study a simple extension of the Standard Model motivated by composite Higgs models, in which a doubly charged scalar decays to W+ t b, resulting in a 4t-like signature from pair production. We train neural networks to differentiate this BSM signal from the dominant SM backgrounds using jet images and kinematic data. We derive the discovery reach and expected exclusion limit at the LHC. In this context we highlight some key differences between standard image recognition and its application to particle physics.

MSc. Yanick Thurn
Title: Analytic continuation of lattice quantum Monte-Carlo (QMC) simulations unsing neural networks

In quantum many-body physics, the analytic continuation of Greens' functions is a well-known problem. The problem is ill-posed in the sense that the transformation kernel becomes chaotic for large energies and thus small noise creates huge differences in the resulting spectral density function. Some techniques in the field of machine learning, in particular neural networks, are known for handling this kind of problem. A network is trained to determine the spectral density from the imaginary part of the Greens function given by quantum Monte Carlo simulations. The network is able to recover the overall form of the spectral density function, even without adding constraints such as normalization and positive definiteness. There is no need to encode these constraints as regularizations since they are reflected automatically by the solution provided by the network. This indicates the correctness of the inversion kernel learned by the neural network.

After the seminar a barbecue will take place on Campus Hubland Nord if weather permits it. In case of bad weather we will meet at the Greek restaurant.