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 a CUDA 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 OTKA-NF-104034 grant of OTKA.

We are also grateful to our past funding agencies, 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 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 Penner-type (logarithmic) potential.

• 11 February 2015, Fidel I Schaposnik Massolo (La Plata, Argentina)

  D5-brane 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 D5-branes 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 D5-branes correspond to Wilson loops in the k-th 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 : Three-Point Functions in N=4 SYM theory

  The discovery of integrability in the planar N=4 Super-Yang-Mills 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 three-point 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 semi-classical 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

  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 Gubser-Mitra 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 Sachs-Wolfe 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 sub-theory of conformastat space-times.

  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

  Alyosha Zamolodchikov a sinh-Gordon 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 cross-over folyamokra. Otletet a c-tetelen keresztul megfogalmazva eljarast adunk a cross-overt 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 Riemann-Hilbert problema helyett egy, a TBA univerzalis megfogalmazasabol kapcsolodo diagrammatikus konstrukciobol megkonstrualjuk.

• 11 March 2015, Tamas Kovacs (ATOMKI, Debrecen, Hungary)

• 18 March 2015, Peter Mati (BME, Hungary)

• 1 April 2015, Peter Gnadig (Eotvos)

  Alkalmazhato-e a Biot--Savart-torveny nem zarodo "aramkorokre"?

• 8 April 2015, Richard Szabo (Heriot-Watt University, UK)

• 22 April 2015, Peter Bantay (Eotvos)

• 29 April 2015, Marietta Homor (Eotvos)

• 20 May 2015, Andreas Ringwald (DESY Hamburg)

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

• 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.
  
  
• Freeze-out 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 [hep-lat]].
  
  
• Freeze-out parameters: lattice QCD meets heavy-ion experiments.
  By Sz. Borsanyi, Z. Fodor, S.D. Katz, S. Krieg, C. Ratti, K. Szabo.
  PoS QCD-TNT-III (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 [hep-lat]].
  
  
• 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 [hep-lat]].
  10.1007/JHEP04(2014)132.
  JHEP 1404 (2014) 132.
  
  
• Local CP-violation 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 [hep-lat]].
  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 [hep-lat]].
  
  
• 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 [hep-lat]].
  10.1016/j.physletb.2014.01.007.
  Phys.Lett. B730 (2014) 99-104.
  
  

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.

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. Ask for the fixed rate which should be around 20-22 euros.

Our department is on the Buda side of the Danube very close to the Petofi Bridge and it is about a 30-35 minutes walk from the hotel:

View Larger Map

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 seven-story building on the right. The Department of Theoretical Physics is on the first floor on the Danube facing side of the building: