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
Due to the covid19 pandemic the seminar is currently held in the Ortvay lecture hall allowing for social distancing. Please bring a mask with you.
Time: Wednesdays at 14:15
See the archive for seminars since 2014.

23 September 2020, Tamas Kovacs (Eotvos) slides
Prediction of chaotic time series  a machine learning approach
Recently, it turned out that recurrent neural network (RNN) is an extremely successful concept to forecast nonlinear dynamical systems. However, it is computationally expensive to train all the parameters in a nonlinear optimization problem. In this talk I am going to review a special case of RNNs, the reservoir computing (RC), that fits also perfectly to the task of forecasting. In RC only the output layer must be trained with many few parameters and a cheap linear least square operation. The method will be introduced step by step through practical examples.

30 September 2020, Zoltan Peli (Debrecen) slides
Derivative expansion for computing critical exponents of O(N) symmetric models at NNLO accuracy
We apply the derivative expansion of the effective action in the exact renormalization group (ERG) equation up to fourth order (\partial^4order, NNLO) on the Z_2 and O(N) symmetric scalar models in d=3 Euclidean dimensions. We compute the critical exponents nu, eta and omega using polynomial expansion in the field. We obtain our predictions for the exponents employing two regulators widely used in ERG computations. We find that both regulators produce results in agreement with predictions obtained by the available MonteCarlo and conformal bootstrap methods, but requiring significantly less computational time than those do.

7 October 2020, Gergely Fejos (Eotvos) slides
Order of the color superconducting phase transition
I will present recent results on the finite temperature phase transition of color superconductivity, predicted to exist in dense quark matter. By reviewing renormalization group analyses of ordinary superconductivity, I will generalize its GinzburgLandau functional to QCD and calculate the flow of the free energy in three spatial dimensions via the functional renormalization group technique. The findings show that unlike ordinary superconductivity, the color superconducting phase transition can only be of first order.

14 October 2020, Peter Bantay (Eotvos) slides
Gauge Lattice Theory
We give an overview of some recent advances in the field, with special emphasis on computational issues.

21 October 2020, Sven Moch (Hamburg)
QCD evolution at 1% precision
We review the status and precision of evolution equations in perturbative QCD. We give an overview on the current theoretical status and the calculational techniques used in perturbation theory. We discuss the application of QCD evolution equations in the determination of parton distribution functions in the proton, the strong coupling constant alpha_s and the quark masses m_c, m_b and m_t in global fits. We give an overview of current results and compare to available information from other approaches like lattice QCD.

28 October 2020, Balazs Pozsgay (Eotvos)
TBA

4 November 2020, Josu HernandezGarcia (Eotvos)
GeVscale neutrinos: interactions with mesons and DUNE sensitivity
The simplest extension of the SM to account for the observed neutrino masses and mixings is the addition of at least two singlet fermions (or righthanded neutrinos). If their masses lie at or below the GeV scale, such new fermions would be produced in meson decays. Similarly, provided they are sufficiently heavy, their decay channels may involve mesons in the final state. Although the couplings between mesons and heavy neutrinos have been computed previously, significant discrepancies can be found in the literature. The aim of this talk is to clarify such discrepancies and provide consistent expressions for all relevant effective operators involving mesons with masses up to 2 GeV. As an application, we numerically compute the expected sensitivity of the DUNE near detector to these heavy neutral leptons.

11 November 2020, Gyula Bene (Eotvos)
TBA

18 November 2020, Daniel Nogradi (Eotvos)
Revisiting the semiclassical approximation at high temperature
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: