Ss2024

Tuesday seminars start at 15:15. Friday seminars start at 14:15.

Unless otherwise stated, the seminars will be held in PHY 5.1.34A.

Tue, 16th Apr

Fri, 19th Apr

Tue, 23rd Apr

  • Time: 15:15
  • Speaker: Thomas Sterr (Master Vortrag)
  • Title: Estimating cellular background contributions from bulk transcriptomics data

Fri, 26th Apr

Tue, 30th Apr

  • Time: 15:15
  • Speaker: Joshua Lin (MIT)
  • Invited by: Bali
  • Title: Gauge-invariant renormalization schemes for lattice-HQET operators
Abstract Abstract: The fact that the mass of the bottom quark is much larger than the typical scale of QCD interactions is hugely beneficial, and allows for a Heavy-Quark Effective Theory (HQET) description of bottom-quark physics. Discretising HQET in lattice-QCD poses unique challenges, such as dealing with the static quark self-energy divergence. Renormalizing four-quark HQET operators in a regulator-independent scheme is a necessary step to extracting physical properties of bottom-hadrons from lattice-QCD calculations, such as their lifetimes and their mixing rates. I will present a new calculation of matching conditions for a gauge-invariant, position-space scheme for four-quark HQET operators.
  • Literature:

Fri, 3rd May

  • Time: 14:15
  • Speaker: Marco Huber (Master Vortrag)
  • Title: Improving Optimization Efficiency for the MHN Model
Abstract The MHN model is a cancer progression model whose parameters are optimized with the use of patient data. Particularly when considering complex tumors with many possible mutations, the computational cost of each iteration of this optimization procedure is significant. In this talk, I will investigate the effect of different optimizers onto the convergence speed. Using these results, a decrease in the runtime has been observed.
  • Literature:

Tue, 7th May

  • Time: 15:15
  • Speaker: Luchang Jin (University of Connecticut) ONLINE
  • Title: Finite volume effects and operator renormalization in lattice QCD + QED calculation
Abstract I will report recent progress in the lattice QCD calculation of the QED corrections to meson leptonic decay. In particular, I will discuss the treatment of QED interactions in the finite volume lattice QCD calculation, and the study of operator renormalization in the presence of the QED interactions via operator product expansion (OPE). The QED corrections to meson leptonic decay combined with an accurate lattice QCD determination of meson decay constants $f_\pi$, $f_K$ allow us to extract CKM matrix elements $V_{us}$ and $V_{ud}$ from experimental measurement of meson leptonic decay width.
  • Literature:

Fri, 10th May

Tue, 14th May

  • Time: 15:15
  • Speaker: John Bulava (Bochum)
  • Invited by: Collins
  • Title: The two-pole nature of the Lambda(1405) from lattice QCD
Abstract Although experimentally well-established, the nature of the Lambda(1405) hyperon resonance has long been a mystery. Constituent quark models have difficulty accommodating its low mass, while approaches based on chiral effective theory typically predict an additional state, the Lambda(1380), which is broad and difficult to identify. I will present the first lattice QCD computation of the coupled-channel $\pi\Sigma-\bar{K}N$ scattering amplitude in the Lambda(1405) channel, which employs quark masses so that the $\pi\Sigma$ threshold is approximately 1380 MeV. This enables the unambiguous identification of the Lambda(1380) in addition to the Lambda(1405), thus supporting the exotic meson-baryon `molecule' interpretation.
  • Literature:

Fri, 17th May

Tue, 21st May

lecture free day after Pentecost

Fri, 24th May

  • Time: 14:15
  • Speaker: Vitaly Magerya (KIT)
  • Invited by: Ahmed
  • Title: Calculating massive two-loop five-point amplitudes for qq->ttH production
Abstract Massive two-loop amplitudes for 2->3 scattering processes are at the edge of what is possible with current computational methods. The two limiting factors are the ability to solve large systems of integration-by-parts relations and the ability to evaluate Feynman integrals numerically. In this talk I want to go into the details of how both problems are tamed in the recent calculation of 2-loop amplitudes for qq->ttH production.
  • Literature: 2402.03301, 2211.03572, and 2305.19768.

Tue, 28th May

  • Time: 15:15
  • Speaker: Abhishek Mohapatra (TUM)
  • Invited by: Bali
  • Title: One Born Oppenheimer Effective Theory for all Exotics
Abstract The XYZ exotic states discovered in the hadronic sector with two heavy quarks constitute one of the most important open problems in particle theory. In this talk, I show that an effective field theory derived from QCD, the Born Oppenheimer effective field theory (BOEFT), can describe exotics of any composition. I show the results of general Schr\"odinger coupled equations for arbitrary angular momentum of the light degrees of freedom. The coupled equations describe hybrids, tetraquarks, pentaquarks, doubly heavy baryons, and quarkonia in leading order, including nonadiabatic terms. Additionally, I also present the results of the predicted multiples, corresponding selection rules, and expressions of the nonperturbative gauge invariant correlators, which are the input of the BOEFT: static energies, generalized Wilson loops, gluelumps, and adjoint mesons that should be calculated on the lattice. Moreover, I show for the first time new results on the behavior of static energies at short distances and mixing with the threshold at long distances based on BOEFT. As an application of this BOEFT. I show results for the hybrid spectrum and decay to quarkonium.
  • Literature:

Fri, 31st May

  • Time: 14:15
  • Speaker: Maximilian Gaschler (Master Vortrag)
  • Title: Gregory-Laflamme instability of small black holes in Anti-de Sitter space.
Abstract Below a certain Schwarzschild radius, black holes in Anti-de Sitter space are unstable. We conduct a numerical study to find the end state of this instability, which is currently unknown. Due to the AdS/CFT correspondence, this could also have consequences for quantum field theories. In this talk, I will present the origin of the instability and possible scenarios for the evolution of small black holes. I will also show the numerical methods of our investigation.
  • Literature:

Tue, 4th to Fri, 7th Jun

  • Speaker: Ekta Chaubey Sotnikov (Bonn)
  • Bernhard Heß Preis Lectures 2024
  • Times:

4th June at 15:15

5th June at 15:15

6th June at 14:15

7th June at 14:15

  • Title: Taming massive Feynman integrals for precision physics
Abstract As the Large Hadron Collider accumulates data, the significance of precise predictions by particle physicists becomes increasingly crucial. The computation of scattering amplitudes serves as an im- portant link between theoretical predictions and experimental measurements. To meet the increas- ing demand for precision in theoretical computations, the inclusion of contributions from massive particles becomes imperative. However, the inclusion of massive corrections into the analytical com- putations makes the computation of the contributing Feynman integrals extremely challenging and often calls for a deep mathematical understanding of their analytic structure. For instance, with the inclusion of massive particles, we often need to go beyond the simplest class of functions, common- ly referred to as multiple polylogarithms, and incorporate functions corresponding to elliptic curves, thereby linking Feynman integrals with algebraic geometry. During these set of lectures, we will learn about various aspects of multi-loop computations as well as about modern techniques for handling massive Feynman integrals required for precision physics.
  • Literature:

Tue, 11th Jun

Fri, 14th Jun

Tue, 18th Jun

  • Time: 15:15
  • Speaker: Alexei Bazavov (CERN, Michigan State)
  • Invited by: von Manteuffel
  • Title: Highly Improved Staggered Quarks on anisotropic lattices
Abstract The Highly Improved Staggered Quark (HISQ) action introduced by the HPQCD collaboration in 2007 is a fermion discretization scheme that in the course of last fifteen years has been successfully applied in a variety of lattice QCD calculations, including determination of quark masses and the strong coupling constant, properties of the strongly interacting matter at extreme conditions, hadronic contribution to the muon anomalous magnetic moment, to name a few. A large library of gauge field ensembles at zero and finite temperature has been generated over the years that cover a range of lattice spacings and light quark masses, including at the physical point, that allow for well-controlled chiral-continuum extrapolations. Those HISQ gauge field ensembles are isotropic, i.e., the lattice spacing in physical units is the same in the temporal and spatial directions (which is also true for the majority of discretization schemes used in the lattice QCD community). However, there are phenomenologically relevant problems where anisotropic ensembles may be preferable. The one of my immediate interest is reconstruction of heavy quarkonia spectral functions, that encode all information about the behavior of these states in the quark-gluon plasma medium, from Euclidean lattice correlators. In general, such spectral reconstruction is an ill-defined inverse problem where resolution in the temporal direction plays a crucial role. In this talk I discuss the ongoing efforts on starting a program of calculations with the anisotropic HISQ (aHISQ) action.
  • Literature:

Fri, 21st Jun

  • Time: 14:15
  • Speaker: Stephan Durr (Wuppertal)
  • Invited by: Collins
  • Title: Surprises with Karsten-Wilczek and Borici-Creutz fermions
Abstract TBD
  • Literature:

Tue, 25th Jun

  • Time: 15:15
  • Speaker: Joshua Davies (Liverpool)
  • Invited by: Ahmed
  • Title: Precision HH predictions: QCD and EW corrections
Abstract In this talk I will discuss some recent work on the use of expansions in various kinematic limits to make sense of complicated multi-scale multi-loop amplitudes. In particular, I will discuss how expansions in the high-energy and small-t limits can provide a good approximation of the virtual amplitude for di-Higgs production in gluon fusion. I will discuss two-loop amplitudes for both QCD and EW corrections, and some early work on three-loop QCD corrections.
  • Literature:

Fri, 28th Jun

Tue, 2nd Jul

  • Time: 15:15
  • Speaker: Torsten Zache (Innsbruck)
  • Invited by: Andreas Schaefer
  • Title: Q-deformed truncation of non-abelian lattice gauge theories in the Hamiltonian formulation
Abstract Simulating the real-time dynamics of gauge theories is an outstanding challenge where the use of future quantum computers promises a practical advantage over classical computers. A prerequisite for quantum simulation is to reformulate gauge theories in a way suitable for quantum information processing. In this talk, I will discuss an approach to truncate non-abelian lattice gauge theories based on a generalisation of the Kogut-Susskind Hamiltonian formulation. After reviewing how to truncate the underlying Lie algebra using a so-called q-deformation which produces a finite-dimensional Hilbert space, I will demonstrate how this approach allows us to construct efficient quantum algorithms for real-time evolution. Finally, I will present our recent and ongoing work to test the physics of (de)confinement in this truncation using variational tensor network simulations.
  • Literature:

Fri, 5th Jul

Tue, 9th Jul

  • Time: 15:15
  • Speaker: Thomas Gehrmann (Zurich)
  • Invited by: von Manteuffel
  • Title: Precision theory for high energy collider physics
Abstract Benchmark cross sections are measured to high accuracy at the LHC. They provide in-depth information on the underlying particle dynamics, and they can be used for precision determinations of Standard Model parameters and in indirect searches for new physics effects. To match the quality of the experimental data, equally precise theory predictions are needed, which are obtained by going to high orders in perturbation theory. We describe techniques and recent results for precision calculations and discuss their impact for particle phenomenology on selected examples.
  • Literature:

Fri, 12th Jul

  • Time: 14:15 ONLINE
  • Zoom: number 926 6896 3987, password 545504
  • Speaker: Daniel Winderl (Master Vortrag)
  • Title: Self-supervised deep learning for subcellular spatial transcriptomics data
Abstract Recent experimental developments facilitate the quantification of spatial RNA distributions via spatial transcriptomics (ST). In preliminary works, I studied different deep learning approaches for the analysis of ST data with (sub-)cellular resolution. One specific application is the segmentation of cells, for which I studied SCS. SCS’s results showed high variability, motivating further methodological developments. For this purpose, I tested masked autoencoders, which are an instance of self-supervised learning. In my master thesis, I will further explore whether self-supervision can improve deep learning methods for spatial transcriptomics data.
  • Literature:

Tue, 16th Jul

Fri, 19th Jul

Tag der Physik

Tue, 17th Sep

  • Time: 15:15 via ZOOM
  • Speaker: Maximilian Weber (FAU Erlangen)
  • Invited by: T. Wettig
  • Title: Variations on the Maiani-Testa Approach and its Translation to the Lattice