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 funded by the Lendulet grant of the Hungarian Academy of Sciences and by the OTKANF104034 grant of OTKA.
We are also grateful to our past funding agencies, 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 seminars of the Department of Theoretical Physics
Location: 2nd floor, 2.54, Novobatzky room
Time: Wednesdays at 14:15
See the archive for seminars in past years.

28 January 2015, Chaiho Rim (Sogang University, South Korea)
Some applications of random matrix models slides
Random matrix models are used to describe (1) statistical variance of multivariables using Gaussian pontential (2) 2d quantum gravity using polynomial potential (3) regular and irregular conformal block using Pennertype (logarithmic) potential.

11 February 2015, Fidel I Schaposnik Massolo (La Plata, Argentina)
D5brane boundary reflection factors slides
a We compute the strong coupling limit of the boundary reflection factor for excitations on open strings attached to various kinds of D5branes that probe AdS(5)xS(5). We study the crossing equation, which constrains the boundary reflection factor, and propose that some solutions will give the boundary reflection factors for all values of the coupling. Our proposal passes various checks in the strong coupling limit by comparison with diverse explicit string theory computations. In some of the cases we consider, the D5branes correspond to Wilson loops in the kth rank antisymmetric representation of the dual field theory. In the other cases they correspond in the dual field theory to the addition of a fundamental hypermultiplet in a defect.

18 February 2015, Yunfeng Jiang (Saclay, France)
Integrability in AdS/CFT : ThreePoint Functions in N=4 SYM theory
The discovery of integrability in the planar N=4 SuperYangMills theory and its AdS dual has triggered a lot of progress in recent years. Equipped with powerful integrability based techniques, it is now possible to compute many interesting quantities such as the spectrum, Wilson loop and scattering amplitudes of the theory at any value of the coupling constant. In this talk, I will explain how to compute threepoint functions in the planar N=4 SYM theory at tree level and one loop in perturbation theory using Bethe ansatz. I will also discuss the semiclassical limit and the comparison with the computation at strong coupling.

25 February 2015, Robert Wald (Enrico Fermi Institute, Chicago)
Dynamic and Thermodynamic Stability of Black Holes and Black Branes slides
I describe work with with Stefan Hollands that establishes a new criterion for the dynamical stability of black holes in $D \geq 4$ spacetime dimensions in general relativity with respect to axisymmetric perturbations: Positivity of the canonical energy, $\mathcal E$, on a subspace of linearized solutions that have vanishing linearized ADM mass, momentum, and angular momentum at infinity and satisfy certain gauge conditions at the horizon implies mode stability. Conversely, failure of positivity of $\mathcal E$ on this subspace implies the existence of perturbations that cannot asymptotically approach a stationary perturbation. We further show that $\mathcal E$ is related to the second order variations of mass, angular momentum, and horizon area by $\mathcal E = \delta^2 M  \sum_i \Omega_i \delta^2 J_i  (\kappa/8\pi) \delta^2 A$. This establishes that dynamic stability of a black hole is equivalent to its thermodynamic stability (i.e., its area, $A$, being a maximum at fixed ``state parameters'' $M$, $J_i$). For a black brane, we prove that a sufficient condition for instability is the failure of the Hessian of $A$ with respect to $M$, $J_i$ to be negative, thus proving the GubserMitra conjecture. We also prove that positivity of $\mathcal E$ is equivalent to the satisfaction of a ``local Penrose inequality,'' thus showing that satisfaction of this local Penrose inequality is necessary and sufficient for dynamical stability.

25 February 2015, George Sparling (Pittsburgh)
Searching for structure: A tribute to Doctor Zoltan Perjes  the universe, large and small.
One hundred years after the final formulation of general relativity by Albert Einstein, the quest to comprehend his theory continues. Doctor Zoltan Perjes was a master of the theory, constantly stretching its boundaries. He would work in cosmology, the study of the whole universe, always being concerned with relating the abstract theory to measurable quantities, such as the SachsWolfe effect. He would also work locally dealing with isolated bodies, such as stars, testing their stability and trying to construct realistic models. He had his own speciality the theory of space times with a timelike symmetry, for which he developed his beautiful triad formalism and the subtheory of conformastat spacetimes.
In this talk I will present two recent results of mine and my colleague Jonathan Holland, which I believe would have been dear to Zoltan's heart: First an analysis of Bach flat metrics of a split form: in particular it is proved that all such have a symmetry. Second a discussion of the new approach to cosmology that we have initiated in the last two years: in our basic model a key role is played by a timelike conformal symmetry. This new theory leads to a remarkable new picture of the relationship between local and global cosmology and brings to bear for the first time major modern mathematical tools: the theory of Fano manifolds.

4 March 2015, Gabor Takacs (BME, Hungary)
Form faktorok a lepcsohazbol slides
Alyosha Zamolodchikov a sinhGordon modell termodinamikai Bethe Ansatz egyenletenek analitikus elfolytatasaval lepcsos renormalasi csoport folyamot konstrualt, amivel sikerult alternativ leirast adnia a konform minimalis modellek (multikritikus Ising modellek) kozotti crossover folyamokra. Otletet a ctetelen keresztul megfogalmazva eljarast adunk a crossovert leiro terelmeletek egzakt form faktorainak konstrukciojara. A feltarulo struktura felveti annak lehetoseget, hogy szamos integralhato terelmelet egzakt form faktorait a bootstrap jelentette igen bonyolult matrix RiemannHilbert problema helyett egy, a TBA univerzalis megfogalmazasabol kapcsolodo diagrammatikus konstrukciobol megkonstrualjuk.

11 March 2015, Tamas Kovacs (ATOMKI, Debrecen, Hungary)
The chiral and the Anderson transition in QCD slides
Recently we have been studying an Andersontype localizationdelocalization transition in the spectrum of the Dirac operator describing quarks in the quarkgluon plasma. In the talk I summarize the latest results about the properties of this transition and its possible implications on the thermodynamics of QCD and other QCDlike theories.

18 March 2015, Peter Mati (BME, Hungary)
The Vanishing Beta Function Curves from the Functional Renormalisation Group
We will discuss the derivation of the so called Vanishing Beta Function curves which can be used to explore the fixed point structure of the theory under consideration. This can be applied to the O(N) symmetric theories essentially for arbitrary dimensions (D) and field component (N). We will show the restoration of the MerminWagner theorem for theories defined in D <= 2 and the presence of the Wilson Fisher fixed point in 2<D<4. Triviality is found in D>4. Interestingly, one needs to make an excursion to the complex plane to see the triviality of the four dimensional O(N) theories. The large N analysis shows a new fixed point candidate in 4<D<6 dimensions which turns out to define an unbounded fixed point potential supporting the recent results by R. Percacci and G. P. Vacca. Corresponding paper: http://arxiv.org/abs/1501.00211

1 April 2015, Peter Gnadig (Eotvos)
Alkalmazhatoe a BiotSavarttorveny nem zarodo "aramkorokre"?

8 April 2015, Richard Szabo (HeriotWatt University, UK)
Nonassociative Quantum Mechanics slides
We briefly review recent developments from string theory which suggest that nongeometric string backgrounds experience a nonassociative deformation of spacetime geometry. A geometrisation of this frame leads to a sigmamodel for closed strings propagating in an effective target space that is the phase space of the original compactification manifold. Quantization of the sigmamodel produces an explicit nonassociative starproduct algebra on functions on phase space, which is related to the quantization of NambuPoisson structures. We use this formalism to develop a phase space formulation of nonassociative quantum mechanics, and demonstrate that, against all odds, a consistent formulation seems indeed possible. Our approach is completely quantitative and adds to previous qualitative discussions of nonassociativity in quantum mechanics, and it moreover avoids previous nogo theorems.

22 April 2015, Peter Bantay (Eotvos)
Replication identities in 2D Conformal Field Theory slides
We discuss an approach to replication identities satisfied by conformal characters of a 2D CFT that links them with symmetries of symmetric products, providing a physics interpretation of the Hauptmodul property of Monstruous Moonshine.

29 April 2015, Marietta Homor (Eotvos)
Transport Coefficients and Thermalisation in Classical Field Theories slides
Our first objective is to show a practical method for the determination of viscosity in classical, relativistic field theories. We will discuss the relevant physical quantities in thermalised systems by the example of Phi^4 theory. Furthermore, we recently observed that the thermalisation in itself has interesting properties e.g. the distributions thermalize in a much shorter scale than the temperature. Inspired by this, our second objective is to examine the thermalisation properties of Phi^4 theory from various initial conditions. We propose, that the first correction to the MaxwellBoltzmann distribution is the Tsallis distribution.

20 May 2015, Andreas Ringwald (DESY Hamburg)
Ultralight AxionLike Particles from Strings slides
There are various puzzling observations in sastrophysics which may be explained by the existence of light axionlike particles (ALPs) with a tiny coupling to the known particles of the Standard Model. In this talk, we will discuss how such ALPs and their couplings to the Standard Model may arise naturally from ultraviolet extensions inspired by string theory.
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
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
katz {at} bodri {dot} elte {dot} hu
postdoc
2013 PhD  University of Calcutta, India
2013 postdoc  Eotvos University, Hungary
santanu {at} bodri {dot} elte {dot} hu
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
nogradi {at} bodri {dot} elte {dot} hu
PhD student
2010  Eotvos University, Hungary
apasztor {at} bodri {dot} elte {dot} hu
postdoc
2013 PhD  University of Pecs, Hungary
2013 postdoc  Eotvos University, Budapest
pittler {at} bodri {dot} elte {dot} hu
MSc student
2014  Eotvos University, Hungary
MSc student
2014  Eotvos University, Hungary
PhD student
2010  Eotvos University, Hungary
trombitas {at} ludens {dot} elte {dot} hu
BSc student
2014  Eotvos University, Hungary
Former members
2009 PhD  Eotvos University, Hungary
2010 postdoc  University of Regensburg, Germany
endrodi {at} general {dot} elte {dot} hu
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
kgt {at} fizika {dot} ttk {dot} pte {dot} hu
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
tothbalint {at} szofi {dot} elte {dot} hu
Recent papers

Can the Higgs Impostor Hide Near the Conformal Window?.
By Zoltan Fodor, Kieran Holland, Julius Kuti, Daniel Nogradi, Christopher Schroeder, Chik Him Wong.
10.1142/9789814566254_0002.

Freezeout parameters from electric charge and baryon number fluctuations: is there consistency?.
By S. Borsanyi, Z. Fodor, S.D. Katz, S. Krieg, C. Ratti, K.K. Szabo.
[arXiv:1403.4576 [heplat]].

Freezeout parameters: lattice QCD meets heavyion experiments.
By Sz. Borsanyi, Z. Fodor, S.D. Katz, S. Krieg, C. Ratti, K. Szabo.
PoS QCDTNTIII (2014) 033.

The chiral condensate from the Dirac spectrum in BSM gauge theories.
By Zoltan Fodor, Kieran Holland, Julius Kuti, Daniel Nogradi, Chik Him Wong.
[arXiv:1402.6029 [heplat]].

Charmonium spectral functions from 2+1 flavour lattice QCD.
By Szabolcs Borsanyi, Stephan Durr, Zoltan Fodor, Christian Hoelbling, Sandor D. Katz, Stefan Krieg, Simon Mages, Daniel Nogradi et al..
[arXiv:1401.5940 [heplat]].
10.1007/JHEP04(2014)132.
JHEP 1404 (2014) 132.

Local CPviolation and electric charge separation by magnetic fields from lattice QCD.
By G.S. Bali, F. Bruckmann, G. Endrodi, Z. Fodor, S.D. Katz, A. Schafer.
[arXiv:1401.4141 [heplat]].
10.1007/JHEP04(2014)129.
JHEP 1404 (2014) 129.

Can a light Higgs impostor hide in composite gauge models?.
By Zoltan Fodor, Kieran Holland, Julius Kuti, Daniel Nogradi, Chik Him Wong.
[arXiv:1401.2176 [heplat]].

Full result for the QCD equation of state with 2+1 flavors.
By Szabocls Borsanyi, Zoltan Fodor, Christian Hoelbling, Sandor D. Katz, Stefan Krieg, Kalman K. Szabo.
[arXiv:1309.5258 [heplat]].
10.1016/j.physletb.2014.01.007.
Phys.Lett. B730 (2014) 99104.
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.
In case you are interested you can see a map of GPU cluster installations throughout the world dedicated to Lattice Gauge Theory.
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: