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.

13 February 2019, Andras Laszlo (WignerMTA)
General Relativity experiment with spin polarized particle beams slides
In experimental proposals published in the last two decades, a so called frozen spin storage ring concept emerged, for setting upper experimental bounds to electric dipole moment (EDM) of charged elementary particles with spin. In a recent paper of ours (Class.Quant.Grav.35(2018)175003), a fully covariant general relativistic (GR) calculation was presented on the Earth's gravitational modification effect on the spin transport inside such a frozen spin storage ring. It turns out that in certain configurations, Earth's gravity is expected to produce a similar order of magnitude effect as the aimed EDM sensitivity, and thus it becomes kind of realistic to experimentally see this GR effect. If such an experiment could be conducted, it could provide a novel test of GR: with microscopic particles, at relativistic speeds, along nongeodesic (forced) trajectories, and the tensorial nature of GR would be at test, not merely the gravitational drag. In more technical terms: the GR correction to the so called Thomas precession could be tested in lab. For details on the experimental idea, we refer to: arXiv:1901.06217 (Proceedings of Spin2018 Conference).

20 February 2019, Ferenc Pittler (Bonn)
A novel mechanism for dynamical generation of elementary fermion masses slides
The Standard Model (SM) is very successful in describing a plethora of low energy phenomena, however it is unable to explain the electroweak scale naturalness and the fermion mass hierarchy problem. In this talk we numerically verify an intrinsically nonperturbative mechanism for elementary fermion mass generation advocated in 1402.0389 using lattice QCD techniques. This mechanism takes place in nonAbelian gauge models if fermionic chiral symmetries are explicitly broken at the UV cutoff scale and an exact invariance acting on both fermions and scalars forbids power divergent fermion mass corrections. We argue that a complete, composite Higgslike beyond SM (BSM) scenario can be built using this mass generation mechanism. We also discuss differencessimilarities with respect to the current BSM models studied with lattice simulations.

27 February 2019, Mate Csanad (Eotvos)
The RHIC(+SPS+FAIR+NICA+JPARC) Beam Energy Scan Program slides
The RHIC beam energy scan program, complemented by similar programmes at other accelerators, allows for the investigation of the phase diagram of QCD matter by varying the beam energy in the region where the change from crossover to first order phase transition is suggested to occur. The nature of the quarkhadron transition can be studied through analyzing the spacetime structure of the hadron emission source. Many measurements were performed in the recent years, from spectra and yields through fluctuations and anisotropies to intermittency and quantumstatistical correlations. These as of now show a controversial picture, and in this talk, we will go through the plethora of results, with special focus on BoseEinstein correlations.

6 March 2019, Koushik Mandal (Eotvos)
Fully Hadronic SUSY Search in CMS slides
Supersymmetry (SUSY) is one of the best motivated and most compelling theories going beyond Standard Model (SM) physics. In the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC), SUSY searches have been extensively carried out exploring the possibility of the existence of the supersymmetric partners of SM particles in a wide mass range studying diverse experimental signatures. Given the naturalness theory, the scalar top quarks and the gluino are of particular interest. Depending on the final state of the scalar top and gluino decays, search channel could be leptonic, hadronic or mixed. Because of the higher expected rate at the LHC, we studied the fully hadronic final state containing missing transverse momenta and multiple jets. A comprehensive study of stop and gluino searches will be presented, underlining the method to tag top quark decays and to estimate from the LHC data the SM background rate.

13 March 2019, Ruchi Chudasama (Eotvos)
Physics of ultraperipheral collisions with CMS experiment slides
Moving highlycharged ions carry strong electromagnetic fields that act as a beam of photons. In collisions at large impact parameters, hadronic interactions are not possible, and the ions interact through photonphoton and photonion collisions known as ultraperipheral collisions (UPCs). Photonphoton interactions provide a wide range of opportunities from the test of Quantum ElectroDynamic (QED) to search for physics beyond Standard Model (SM). We provide the evidence for light by light scattering and search for axionlike particles using high photon fluxes from PbPb collisions. On the other hand, photonion processes can probe the gluon distribution in proton and heavyions down to Bjorken x values 10^{6}, far smaller than can be otherwise studied. In this lowx regime, nonlinear QCD effects (gluon recombination) may become important, possibly leading to the saturation of the parton distribution functions. We probe the parton distribution inside proton by studying the exclusive upsilon photoproduction in pPb collisions.

20 March 2019, Antal Jakovac (Eotvos)
Bound states in quantum field theory: an FRG study
In the talk we review the traditional approaches to define bound states in quantum theories. In the example of QED with two oppositely charged fermionic fields, we demonstrate the construction of an effective model that contains bound states, and which reproduces the fermionic observables of the original model. Using numerical analysis in the nonrelativistic limit, we argue that considerable simplifications can be made, still maintaining a reasonable accuracy in the computation of the ground state energy.

27 March 2019, Gergely Marko (Eotvos)
Magnetic field dependence of the NJL coupling from lattice QCD slides
Chiral effective models of strong interactions struggle to capture the inverse magnetic catalysis observed in continuum extrapolated lattice results. One recent trend is to incorporate absent degrees of freedom by making effective model parameters depend on B. We try to improve on this approach by deducing the magnetic field dependence of the Nf=2 (P)NJL coupling directly from lattice observables. We carried out full lattice QCD simulations for the baryon octet masses as a function of the magnetic field using staggered fermions. A continuum extrapolated result is obtained in the eB < 0.6 GeV^2 region. Using a simple nonrelativistic quark model we infer constituent quark masses from the baryons which in turn serve as inputs to obtain the Bdependent coupling. We then solve the (P)NJL model to assess the effect of the Bdependent coupling on the pseudocritical temperature of the chiral phase transition.

12 April 2019, Slava Rychkov (IHES, Ecole Normale Superieure Paris)
Walking, weakly firstorder phase transitions, and complex CFTs
Most people have heard that the 2d Potts model with Q=5 states has a first order phase transition, but not everyone knows that the correlation length at this phase transition is 2500 lattice spacings. We will review "walking RG" behavior in gauge theories and connect it to Type II weak firstorder phase transitions in statistical physics. Despite appearing in very different systems (QCD below the conformal window, the Potts model, deconfined criticality) these two phenomena both imply approximate scale invariance in a range of energies and have the same RG interpretation: a flow passing between pairs of fixed point at complex coupling, dubbed "complex CFTs". Observables of the real walking theory are approximately computable by perturbing the complex CFTs. The general mechanism will be illustrated by a specific and computable example: the twodimensional Qstate Potts model with Q > 4. Based on 1807.11512 and 1808.04380.

24 April 2019, Laurent Lellouch (CNRS, AixMarseille U)
Hadronic vacuum polarization contribution to the muon magnetic moment from lattice QCD
In the early 2000s, the anomalous magnetic moment of the muon, a_mu=(g_mu2)/2, was measured with a remarkable precision of 0.54ppm. Since those results were published, a discrepancy of more than 3 standard deviations has persisted between the standard model (SM) prediction and experiment. At present theoretical and experimental uncertainties are close in size. However, a new experiment underway at Fermilab is aiming to reduce the experimental uncertainty on a_mu by 4. To leverage this future measurement and possibly claim the presence of new fundamental physics, it is imperative to reduce and fully control the uncertainties in the SM prediction. After an introduction to the role that anomalous magnetic moments play in testing the SM and a discussion of the current experimental and theoretical status of a_mu, I will present a lattice QCD calculation of the contribution to this quantity that most limits the precision of its SM prediction.

8 May 2019, Mordehai Milgrom (Weizmann Institute, Israel)
MOND
TBA

15 May 2019, Robert Harlander (Aachen)
TBD
TBA

29 May 2019, Sho Iwamoto (Padova)
TBA
TBA
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: