Lattice Gauge Theory group
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 OTKANF104034 grant of OTKA and the EU Framework Programme 7 grant (FP7/20072013)/ERC No 208740.
Research
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
Seminar
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 temperaturedependence 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 noninteracting 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 AntideSitter (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 nonrelativistic 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 EinsteinMaxwellHiggs system plus a gauge fixing term for diffeomorphism, which may be interpreted as a holographic dual of a general nonrelativistic 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 COVID19

15 April 2020, Sven Moch (Hamburg University)
Cancelled because of COVID19

22 April 2020, Kornel Kapas (Eotvos)
Cancelled because of COVID19

13 May 2020, John Gracey (Liverpool)
Cancelled because of COVID19

20 May 2020, Masanori Hanada (Southampton)
Cancelled because of COVID19

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.
For students
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) nonlinear sigma model with topological term
 Beyond Standard Model  technicolor
People
assistant professor
2009 PhD  University of Pisa, Italy
20102010 postdoc  IPhT/CEASaclay, France
20102012 postdoc  University of Zaragoza, Spain
20122015 postdoc  ATOMKI, Debrecen, Hungary
20152018 postdoc  Eotvos University, Budapest, Hungary
PhD student
2018 Eotvos University, Hungary
professor
2001 PhD  Eotvos University, Hungary
20012003 postdoc  DESY, Hamburg, Germany
20032005 postdoc  University of Wuppertal, Germany
20062012 assistant professor  Eotvos University, Hungary
2012 professor  Eotvos University, Hungary
assistant professor
2005 PhD  University of Leiden, the Netherlands
20052007 postdoc  University of Wuppertal, Germany
20072009 postdoc  UCSD, USA
20092011 senior research fellow  Eotvos University, Budapest
2011 assistant professor  Eotvos University, Budapest
postdoc
2015 PhD  Eotvos University, Hungary
20162018 postdoc  Wuppertal University, Germany
2018 postdoc  Eotvos University, Hungary
PhD student
2016 Eotvos University, Hungary
PhD student
2018 Eotvos University, Hungary
Former members
2009 PhD  Eotvos University, Hungary
20102015 postdoc  University of Regensburg, Germany
2016 Emmy Noether group leader  University of Frankfurt, Germany
1996 PhD  UCLA, USA
19961998 postdoc  University of Colorado, Boulder, USA
19982000 postdoc  University of Leiden, the Netherlands
20002002 postdoc  DESY, Zeuthen, Germany
20022011 professor  University of Pecs, Hungary
2011 senior researcher  ATOMKI, Debrecen, Hungary
2013 PhD  University of Calcutta, India
20132016 postdoc  Eotvos University, Hungary
2016 postdoc  National Chiao Tung University, Taiwan
2013 PhD  University of Pecs, Hungary
20132016 postdoc  Eotvos University, Budapest
2017 postdoc  Bonn University, Germany
2014 MSc  Eotvos University, Hungary
20052006 research assistant  University of Wuppertal, Germany
2007 assistant lecturer  University of Pecs, Hungary
2010 PhD  Eotvos University, Hungary
2010 postdoc  University of Wuppertal, Germany
2017 PhD  Eotvos University, Hungary
2017 postdoc  Wuppertal University, Germany
PhD student
2015 PhD  Eotvos University, Hungary
Publications
Computing
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.
For visitors
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: