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 September 2018, Zsolt Frei (Eotvos)
The road to the detection of gravitational waves, and ELTE's contribution to the quest
I will briefly summarise what we all know by now about gravitational waves (GW) as a prediction of general relativity, the history of searching for the waves, and some technical details of the Laser Interferometer Gravitationalwave Observatory (LIGO), where the group I formed participated since 2007.
I will tell you about our contribution to the data search: we have been an active member of the socalled "burst" group, where we are searching for transienttype signals in the noisy data stream of the detector. We have came up with two new search methods, the "Locust" and "Hough" algorithms. We also contributed to the experiment by developing, making and installing infrasound detectors at both the Hanford and Livingston sites. These detectors are increasingly important to measure the srength of gravity gradient noise, so I will spend some time to elaborate on this topic. Lately, we are also contributing to the identification of possible electromagnetic (EM) counterparts of the newly detected GW sources: binary neutron stars. We have developed a new galaxy catalog for LIGO, containing 2.5 million galaxies (compared to the 50.000 galaxies in the catalog LIGO used before). Some of our partners actually found the EM counterparts of the 2018 August event using our data.
I will conclude with our current work and plans for the future: launching 9 small satellites to lowEarth orbit within the next 5 years to detect gammarays originating from binary neutron star merges and using these detections to precisely and promptly locate (triangulate) the position of the sources of the emerging GWs on the sky for subsequent EM observations.

19 September 2018, Ankita Mehta (Eotvos)
Study of doubleparton scattering processes using samesign WW events at the CMS experiment slides
Doubleparton scattering (DPS) processes include the simultaneous occurrence of two distinct hard partonparton interactions within in a single protonproton collision. These interesting physics processes could provide valuable information on the distribution of partons inside the proton in the transverse direction and act as a background for SM and new physics searches at the LHC. This presentation is based on the results obtained from the first search for samesign WW production via DPS processes, based on protonproton collision data at a centerofmass energy of 8 TeV. The decay of two W bosons is considered in dimuon and electronmuon final states. A multivariate analysis is used to discriminate the single from different background processes. Obtained results on the production cross section for samesign WW via DPS and effective cross section parameter for DPS processes are compared with existing measurements and predictions from MC event generators.

26 September 2018, Attila Pasztor (Eotvos)
QCD thermodynamics at finite density from imaginary chemical potential slides
I will present a minireview of some recent lattice QCD results on the bulk thermodynamic properties of QCD matter at finite temperature and small nonzero chemical potential. I will mostly focus on observables relevant for the RHIC Beam Energy Scan.

3 October 2018, Keming Shen (WignerMTA)
Hadronization within NonExtensive Approaches slides
However Tsallislike distributions describe well the momentum spectra measured in highenergy nuclear collisions, to find the microscopical origin of the nonextensive behavior is not straightforward. Our aim is to explore source of this distribution from the first principles.
We investigated the transverse momentum distributions of various identified charged particles in high energy relativistic heavy ion collisions. I studies the interpretations of these spectra within the nonextensive approaches in details. Results on bestfits show that the mass scaling behaves more explicit with heavier produced hadrons in both pp and heavy ion collisions. In this talk I'll present my recent investigations and new results on massscaling and on specific distributiontypes.

10 October 2018, Zoltan Kokenyesi (Eotvos)
Topological string theory and generalized geometry slides
Generalized geometry is a natural framework for describing geometric and nongeometric flux backgrounds in string compactifications. We study the A and Bmodels of topological string theory and construct a membrane sigmamodel based on a generalized complex structure, which reduces to the A or Bmodels on the boundary in different gauges. Our construction allows the introduction of geometric and nongeometric fluxes as well as an Sduality at the level of the membrane sigmamodel based on the generalized complex structure, and we interpret it as topological Sduality, which exchanges the A and Bmodels. As an outlook we also discuss the relation of membrane sigmamodels in topological Mtheory to generalized geometry of Mtheory.

17 October 2018, Zoltan Trocsanyi (Eotvos)
On the origin of neutrino masses
We consider an anomaly free extension of the standard model gauge group G_SM by an abelian group to G_SM x U(1)_Z. The condition of anomaly cancellation is known to fix the Zcharges of the particles, but two. We fix one remaining charge by requiring that the masses of the left handed neutrinos are generated by a mixing with righthanded neutrinos that obtain their masses through interaction with a new scalar field whose vacuum is broken spontaneously. We discuss some of the possible consequences of the model and ways of constraining the parameter space.

24 October 2018, Zoltan Kunszt (ETH Zurich)
Feynman 100, Neutrino '72 Balatonfured slides
The talk will shortly overview Feynman's unique, ingenious, inspiring scientific achievements as well as his teaching and popular lectures. Feynman's talk at Balatonfuered will be put in historic perspective in conjunction with the discovery of the QCD improved parton model.

25 October 2018, Akio Tomiya (RIKEN)
Phase structure of three flavor QCD in external magnetic fields using HISQ actions slides
We study the phase structure of QCD with three degenerate flavors in external magnetic fields using HISQ actions. The simulations are performed on 16^3. In order to investigate the quark mass dependence of the QCD transition we vary the values of pion masses from m=320 MeV to 80 MeV in the continuum limit. We found no indication of a first order phase transition in the current window of quark masses and external magnetic fields. Unlike to the case with standard staggered fermions inverse magnetic catalysis is always observed above the critical temperature. The microscopic origin of this phenomena as well as the volume effects are further discussed by looking into the Dirac eigenvalue spectrum.

31 October 2018, Dezso Horvath (WignerMTA, Atomki Debrecen)
Recent results in Higgs studies and BSM searches at the LHC slides
The almost halfcentury old theory of particle physics, the standard model (SM) seems to describe most of the experimental data very well. All of its elementary particles were identified and studied, and the discovery of the Higgs boson by ATLAS and CMS at the LHC with the mass m(H) = 125.09 +/ 0.21 (stat.) +/ 0.11 (syst.) GeV proved the validity of the BroutEnglertHiggs mechanism of spontaneous symmetry breaking. In spite of the general quantitative agreement of its predictions with experiment the SM has serious theoretical shortcomings. It cannot account for neutrino oscillations, cannot solve the hierarchy problem (the unnaturally high corrections to the mass of the Higgs boson), there is no place in it for the particles of dark matter, and it cannot explain the lack of antimatter galaxies in the universe. Its gauge couplings are converging but not to the same point at high energies and it cannot include gravity as a gauge interaction. Most of these problems are solved within the frameworks of SM extensions, the most popular of them being supersymmetry. The latter predicts several deviations from the SM, especially in the Higgs sector, where it expects 5 Higgs bosons, three neutral and two charged ones.
Studying the observed Higgs boson may uncover new physics beyond the SM, and thus it is one of the most important programs for the experiments of the Large Hadron Collider. We summarize the activity of CMS and also ATLAS to measure the mass and couplings of the 125 GeV Higgs boson, its decay properties as compared to the SM predictions, and also attempts to check for other Higgs bosons at different masses. Thus far all data collected by ATLAS and CMS agree with the SM, no deviation is found. Great effort is invested by both experiments to study extensions of the standard model and possibly uncover physics beyond it. We shall describe the history of an aborted discovery: a new boson at 750 GeV. Thus the question what new physics is beyond the SM is open yet.
The talk is based on a plenary given on behalf of CMS at the QCD at LHC 2018 Workshop, 2731 August 2018, Dresden (Germany).

7 November 2018, Vladimir Korobov (Dubna)
Precision theory for hydrogen molecular ions
At present theoretical prediction for the spinaveraged frequency of rovibrational transitions in the hydrogen molecular ions (HMI) has reached a relative precision of ~ 7.5 x 10^(12) . On the other hand, recent experiment on pure rotational transition in HD+ has demonstrated the power of the LambDicke regime for precision spectroscopy of the HMI with strong potentiality in the nearest future to achieve a ppt level of spectroscopic accuracy.
The Rydberg constant as it is determined in the CODATA14 adjustment of the fundamental constants has the relative uncertainty 5.9 x 10^(12). At the same time the two new experiments on spectroscopy of hydrogen atom performed at LKB, Paris, and MPQ, Munich, disagree in measuring the Rydberg constant by more than 3sigma!
In our presentation we want to outline the way how the high precision results for the hydrogen molecular ions may be achieved with the help of the effective field theory  the Nonrelativistic QED. At the very end of our talk we intend to discuss the problems, which are to be solved in order to improve (at least threefold) theoretical predictions. That will bring our theory to the level of accuracy which is better than for the present CODATA14 value of the Rydberg constant. And, we hope, that this will help to resolve the discrepancy between the LKB and MPQ experiments as well as to find answers to many other questions related to the fundamental constants.

14 November 2018
No seminar because of CERN25 event of the Academy

21 November 2018, Stefan Teufel (Tubingen)
Nonequilibrium almoststationary states and linear response for gapped quantum systems slides
I report on recent mathematical results concerning the validity of linear response theory at zero temperature for perturbations of gapped Hamiltonians describing interacting fermions on a lattice, e.g. quantum Hall systems. The challenge here is to prove Kubo's formula uniformly in the volume and also for perturbations (like a small constant electric field) that close the spectral gap. Our justification of linear response theory is based on a novel extension of the adiabatic theorem to situations where a timedependent perturbation closes the gap. According to the standard version of the adiabatic theorem, when the perturbation is switched on adiabatically and as long as the gap does not close, the initial ground state evolves into the ground state of the perturbed operator. The new adiabatic theorem states that for perturbations that are either slowly varying potentials or small quasilocal operators, once the perturbation closes the gap, the adiabatic evolution follows nonequilibrium almoststationary states (NEASS) that we construct explicitly.

28 November 2018, Peter Posfay (WignerMTA)
Estimating the variation of neutron star observables by dense nuclear matter properties slides
Description of extreme dense nuclear matter is an active research field, however Lattice QCD calcualtions are challenging for the case of cold dense matter. One needs effective theories to describe this region of the QCD matter and the consistency of these models can be constrained by studying compact astrophysical objects.
Parameters corresponding to effective models of cold nuclear matter (interactions, coupling, mass) affect the observable parameters (mass and radius) of neutron stars. Moreover, detailed studies of QCD phase diagram shows the importance of bosonic quantum fluctuations. In this work we use the Functional Renormalization Group (FRG) method to take into account bosonic quantum fluctuations at fininte chemical potential at zero temperature. We did our caclulations in a system consisting of one fermionic and one bosonic degree of freedom, where the fermions and bosons are coupled together by a Yukawa coupling and the bosons have self interaction terms. We studied the effect of different interaction terms in the Lagrangian on the properties of nuclear matter.

5 December 2018
No seminar because of Zimanyi School

12 December 2018, Gabor Biro (WignerMTA)
Monte Carlo event generators in heavyion physics: a review slides
In the recent decades the rapid technological advancement resulted in larger than ever collision energies, huge, complex detector systems, sophisticated readout systems with immense amount of experimental data, and therefore in the Golden Age of highenergy physics. Along with the experiments also the underlying theories went through a huge development. Nowadays the theoretical calculations are becoming more and more challenging, therefore numerical calculations are getting key importance, with special emphasis not just on the precision but on performance as well.
In this talk I give a review on the Monte Carlo event generators used by the highenergy physics community. Through a historical perspective I introduce today's most widely used frameworks and I highlight the important aspects that emerged during their development and lead to their present state. I give also an outlook to the future's event generators, focusing on our HIJING++ project.
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
You will most likely stay at the Peregrinus hotel in the downtown area of Pest.
The simplest way to get to/from your hotel from/to the airport is by taxi. The fare should be around 30 euros. Uber also works in Budapest :)
Our department is on the Buda side of the Danube very close to the Petofi Bridge and it is about a 3035 minutes walk from the hotel:
You exit your hotel, walk past the Great Market Hall (definitely worth a closer look if you have about half an hour or an hour!) and the Corvinus University, cross the Danube on the Szabadsag Bridge and walk South. You will pass the Budapest University of Technology and the Petofi Bridge and our building will be a redish sevenstory building on the right. The Department of Theoretical Physics is on the first floor on the Danube facing side of the building: