We are the lattice gauge theory group at the Eotvos University in Budapest, part of the Department of Theoretical Physics at the Faculty of Science.

Currently there are nine members and we are seeking new ones. Positions are available for PhD students and postdocs for 2 - 4 years appointments. If you are interested please email Sandor Katz at katz@bodri.elte.hu or Daniel Nogradi at nogradi@bodri.elte.hu.

Our activities are and were funded by various funding agencies for which we are grateful, these include the Lendulet grant of the Hungarian Academy of Sciences, the OTKA-NF-104034 grant of OTKA and the EU Framework Programme 7 grant (FP7/2007-2013)/ERC No 208740.

Our primary interests are:

• Chiral symmetry restoration and deconfinement in QCD with Wilson fermions
• Finite chemical potential
• QCD hadron spectrum
• Eigenvalue distributions of the overlap Dirac operator
• Strongly interacting Higgs sector - strong dynamics
• Conformal gauge theories

Weekly ELFT seminars at the Department of Theoretical Physics

Location: 2nd floor, 2.54, Novobatzky room, 1117 Budapest, Pazmany Peter setany 1/a

If you'd like to receive seminar email announcements please write to nogradi@bodri.elte.hu

Time: Tuesdays at 14:15

See the archive for seminars since 2014.

• 13 September 2022, Gergely Barnafoldi (Wigner) slides

  Estimating elliptic flow coefficient in heavy ion collisions using deep learning

  Machine learning techniques have been employed for the high energy physics community since the early 80s to deal with a broad spectrum of problems. This work explores the prospects of using deep learning techniques to estimate elliptic flow (v2) in heavy-ion collisions at the RHIC and LHC energies. A novel method is developed to process the input observables from particle kinematic information. The proposed deep neural network (DNN) model is trained with Pb-Pb collisions at sNN=5.02 TeV minimum bias events simulated with a multiphase transport model. The predictions from the machine learning technique are compared to both simulation and experiment. The deep learning model seems to preserve the centrality and energy dependence of v2 for the LHC and RHIC energies. The DNN model is also quite successful in predicting the pT dependence of v2. When subjected to event simulation with additional noise, the proposed DNN model still keeps the robustness and prediction accuracy intact up to a reasonable extent.

  N. Mallick et al: Phys.Rev. D105 (2022) 11, 114022

• 20 September 2022, Gabor Etesi (BME) slides

  The universal von Neumann algebra of smooth four-manifolds

  Making use of its smooth structure only, out of a connected oriented smooth 4-manifold a von Neumann algebra is constructed. As a special four dimensional phenomenon this von Neumann algebra contains algebraic (i.e., formal or coming from a metric) curvature tensors of the underlying 4-manifold and the von Neumann algebra itself is a hyperfinite factor of type II_1 hence is unique up to abstract isomorphisms of von Neumann algebras. Over a fixed 4-manifold this universal von Neumann algebra admits a particular representation on a Hilbert space such that its unitary equivalence class is preserved by orientation-preserving diffeomorphisms consequently the Murray--von Neumann coupling constant of this representation is well-defined and gives rise to a new and computable real-valued smooth 4-manifold invariant. Its link with Jones' subfactor theory is noticed as well as computations in the simply connected closed case are carried out.

  Application to the cosmological constant problem is also discussed. Namely, the aforementioned mathematical construction allows to reformulate the classical vacuum Einstein equation with cosmological constant over a 4-manifold as an operator equation over its tracial universal von Neumann algebra such that the trace of a solution is naturally identified with the cosmological constant. This framework permits to use the observed magnitude of the cosmological constant to estimate by topological means the number of primordial black holes about the Planck era. This number turns out to be negligable which is in agreement with known density estimates based on the Press--Schechter mechanism.

  Based on this preprint.

• 27 September 2022, Timea Vitos (Lund University)

  Improving on accuracy and efficiency of Standard Model theory predictions

  In the process of improving experimental accuracy at the LHC and other colliders, it is essential that theory predictions keep up this pace. Specifically, in the search of theories beyond the Standard Model, it is crucial to have a very precise handle on what this successful model actually predicts. This task consists of using the existing tools for various key observables, and also to improve on the scope and efficiency of the tools. In this talk, three important LHC processes and corresponding spin-related observables at NLO electroweak precision are presented: Z+jet, W+jet (also including NNLO QCD) and top-antitop pair production. In addition, the first steps towards a more efficient approach to handle high-multiplicity jet processes is presented, via the next-to-leading colour approximation of the colour matrix.

• 4 October 2022, Zoltan Peli (ELTE)

  Vacuum stability and scalar masses in the superweak extension of the standard model

  We study the allowed parameter space of the scalar sector in the superweak extension of the standard model (SM). The allowed region is defined by the conditions of (i) stability of the vacuum and (ii) perturbativity up to the Planck scale, (iii) the pole mass of the Higgs boson falls into its experimentally measured range. The method can be generalized in a straightforward way to simpe beyond the standard model scenarios such as the singlet scalar extension. We confront our findings against the measured mass of the W boson and the measured width of the Higgs boson. Preliminary results for collider search constraints are also shown.

• 11 October 2022, Rachel Houtz (Durham IPPP)

  TBA

• 18 October 2022, Miklos Vincze (ELTE)

  TBA

• 25 October 2022, Andras Laszlo (Wigner)

  On generally covariant mathematical formulation of Feynman integral in Lorentz signature

  Feynman integral is one of the most promising methodologies for defining a generally covariant formulation of nonperturbative interacting quantum field theories (QFTs) without a fixed prearranged causal background. Recent literature indicates that in such scenario, one needs to consider the problematics in the original Lorentz signature. Lorentz signature Feynman integrals are known, however, to be mathematically ill-defined. The Feynman integral formulation has, however, a differential reformulation: the master Dyson-Schwinger (MDS) equation for field correlators. In this talk we show that with the right choice of variables, the MDS equation is mathematically well defined: the involved function spaces and operators can be defined and their properties can be established. Therefore, MDS equation can serve as a substitute for the Feynman integral, in a mathematically sound formulation of constructive QFT, in arbitrary signature, without a fixed background causal structure. It is also shown that the Wilsonian regularization of the MDS equation can be canonically defined. Our main result is a necessary and sufficient condition for the regularized MDS solution space to be nonempty, which also provides a convergent iterative approximation for the solution. The talk is based on the paper: Class.Quant.Grav.39(2022)185004.

• 29 November 2022, Dimitrios Bachtis (Swansea)

  TBA

Our group offers BSc/MSc diploma, PhD and TDK topics in Lattice Field Theory.

Please contact Sandor: katz@bodri.elte.hu or Daniel: nogradi@bodri.elte.hu in case you are interested.

Current topics include:

• QCD thermodynamics
• 2 and 4 dimensional CFT
• Beyond Standard Model

Since it is tricky to locate all papers by a large number of people whose names are not unique on inspire, you can try various search queries:

• Papers by Sandor Katz and Zoltan Fodor
• Papers by Sandor Katz and Gergely Endrodi
• Papers by Sandor Katz and Matteo Giordano
• Papers by Tamas Kovacs
• Papers by Daniel Nogradi

Our group has access to a number of high performance computer installations in Europe and also maintains several PC and GPU clusters on site in Budapest.

Our department is on the Buda side of the Danube very close to the Petofi Bridge:

The Department of Theoretical Physics is on the sixth floor opposite the Danube facing side of the building: