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. Since 2011 we are an NVIDIA GPU Research Center.

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 {at} bodri {dot} elte {dot} hu or Daniel Nogradi at nogradi {at} bodri {dot} elte {dot} 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

Time: Wednesdays at 14:15

See the archive for seminars in past years.

• 12 February 2020, Tamas G Kovacs (Eotvos) slides

  Instanton interactions in high temperature QCD

  In high temperature QCD instantons are expected to form a dilute gas amenable to analytic treatment. However, the analytically computed temperature-dependence of the topological susceptibility differs significantly from the susceptibility obtained in recent lattice calculations that are relevant to axion physics. A key assumption of the dilute instanton approximation is that instantons (and antiinstantons) form a non-interacting ideal gas. In the talk I will show that spectra of lattice Dirac operators with exact chiral symmetry provide a tool to study instanton interactions above the temperature of the chiral and deconfining transition. A detailed analysis of the lowest part of the Dirac spectrum also yields new insight into the nature of the chiral and deconfining transition and their connection to quark localization.

• 19 February 2020, Matteo Giordano (Eotvos) slides

  Localisation and Goldstone bosons at finite temperature

  I discuss spontaneous breaking of chiral symmetry in gauge theories with fermions at finite temperature when localised modes are present in the spectrum of the Dirac operator. In particular, I show how localised Dirac modes affect the Goldstone poles that are expected to show up in certain correlation functions when a continuous symmetry is spontaneously broken.

• 26 February 2020

  No seminar, talk by Istvan Csabai at the Academy

• 4 March 2020, Sinya Aoki (Yukawa Institute, Kyoto) slides

  Holography from field theories: a realization of AdS/CFT correspondence and beyond

  We argue that the Anti-de-Sitter (AdS) geometry in d+1 dimensions naturally emerges from an arbitrary conformal field theory in d dimensions using the free flow equation. We first show that an induced metric defined from the flowed field generally corresponds to the quantum information metric, called the Bures or Helstrom metric, if the flowed field is normalized appropriately. We next verify that the induced metric computed explicitly with the free flow equation always becomes the AdS metric when the theory is conformal. We also show that the conformal symmetry in d dimensions converts to the AdS isometry in d+1 dimensions after d dimensional quantum averaging. This guarantees the emergence of AdS geometry without explicit calculation.

  We next apply this method to non-relativistic systems with anisotropic scaling symmetries, such as Lifshitz field theories and Schrodinger invariant theories. In consequence we obtain a new hybrid geometry of Lifshitz and Schrodinger spacetimes as a general holographic geometry. We also show that the bulk hybrid geometry is realized by an Einstein-Maxwell-Higgs system plus a gauge fixing term for diffeomorphism, which may be interpreted as a holographic dual of a general non-relativistic system at the boundary.

• 11 March 2020, Mate Lencses (BME) slides

  Chiral Entanglement in Quantum Field Theories in 1+1 Dimensions

  The fixed points of the renormalization group (RG) in quantum field theory can be characterized by conformal field theories (CFTs). In 1+1 dimensions the spectrum of the CFT consists of left and right moving chiral excitations. One can consider the chiral entanglement entropy, the entanglement entropy in ground states between the left and right chiral degrees of freedom. In the fixed point CFT the chiral entanglement entropy is zero and it is finite away from criticality. Moreover, it scales linearly with the system size with a mass dependent slope in the large system limit, and contains a universal constant term, which characterizes the RG flow. Based on the variational Ansatz proposed by J. Cardy, we study the chiral entanglement entropy of ground states along massive RG flows. The analytical results are compared to numerical calculations using the truncated conformal space approach for RG flows around the Ising and tricritical Ising fixed points.

• 18 March 2020, Tamas Kovacs (Eotvos)

  Cancelled because of COVID-19

• 15 April 2020, Sven Moch (Hamburg University)

  Cancelled because of COVID-19

• 22 April 2020, Kornel Kapas (Eotvos)

  Cancelled because of COVID-19

• 13 May 2020, John Gracey (Liverpool)

  Cancelled because of COVID-19

• 20 May 2020, Masanori Hanada (Southampton)

  Cancelled because of COVID-19

• 19 June 2020, Attila Pasztor (Eotvos), online zoom

  Constraining the QCD phase diagram with analytic continuation

  I review the basic methods of analytical continuation from numerical data, and discuss some recent results on the QCD phase diagram obtained with these methods. I also discuss the status of some ongoing projects.

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

Please contact Sandor: katz {at} bodri {dot} elte {dot} hu
or Daniel: nogradi {at} bodri {dot} elte {dot} hu
in case you are interested.

Current topics include:

• QCD thermodynamics
• SU(N) gauge theory with topological lattice action
• O(3) non-linear sigma model with topological term
• Beyond Standard Model - technicolor

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 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 primary resource is a 128 node cluster with two NVIDIA GTX 275 cards in each node, hosted in Budapest. There is also a 60 node cluster with one NVIDIA GTX 8800 card per node.

In addition we also have access to the Juropa cluster and the BlueGene/P installation in Forschungszentrum Juelich, Germany.

Our collaboriation with the University of Wuppertal, Germany also allows us to use several PC and GPU clusters there.

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

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