The IIIrd Nordic Lattice Meeting 2023




It is pleasure to announce the third Nordic Lattice Meeting, which takes place at the University of Stavanger, Norway, between the 6th to 8th of June 2023. We encourage physical participation, in order to facilitate exchange and promote new collaborations. For those who are unable to attend in person a remote option will be provided.

Accommodations on campus can be booked directly at the university hotel Ydalir ( and various hotels are available in the city center, 10 minutes from campus by bus.

Looking forward to seeing you in June,
Alexander & Anders

  • Aleksi Kurkela
  • Alexander Rothkopf
  • Anders Tranberg
  • Anna Kormu
  • Benjamin Jaeger
  • David Weir
  • Deanna Hooper
  • Gaurang Parkar
  • Gerhard Ungersback
  • J Tobias Tsang
  • Jaakko Annala
  • Johan Bijnens
  • Kari Rummukainen
  • Magdalena Eriksson
  • Michele Della Morte
  • Nils Hermansson-Truedsson
  • Oliver Gould
  • Rasmus Larsen
  • Satumaaria Sukuvaara
  • Tobias Rindlisbacher
    • 12:00 PM 1:00 PM
    • 1:00 PM 1:15 PM
      Conveners: Anders Tranberg (UiS - TN - IMF), Alexander Rothkopf (UiS TN IMF)
    • 1:15 PM 3:15 PM
      Plenary session: Plenary I
      • 1:15 PM
        Phase transitions, gravitational waves and the 2-Higgs doublet model 30m
        Speaker: Kari Rummukainen (University of Helsinki)
      • 1:45 PM
        Bubble nucleation and quantum initial conditions in classical statistical simulations 30m

        Classical-statistical lattice simulations provide a useful approximation to out-of-equilibrium quantum field theory, but only for systems exhibiting large occupation numbers, and only for phenomena that are not intrinsically quantum mechanical in nature. In certain special circumstances, it can be appropriate to initialize such real-time simulations with quantum-like zero-point fluctuations. We will revisit these points, and investigate reports that quantum bubble nucleation rates in 1+1 dimensions can be computed through the classical evolution of such a quantum-like initial condition. We find that although intriguing, the reported numerical agreement between classical-statistical simulations and the quantum nucleation rate in 1+1 dimensions is a coincidence, which is not specific to this choice of initialisation, is parameter and lattice cut-off dependent and disappears as the number of space-dimensions increases from 1+1 to 2+1

        Speaker: Gerhard Ungersback (University of Stavanger)
      • 2:15 PM
        Real scalar phase transitions: bubble nucleation, nonperturbatively 30m

        In the Standard Model the electroweak phase transition is a crossover, but in many beyond the Standard Model theories the transition is of first order. Strong first order PTs could produce gravitational waves that might be detectable by the Laser Interferometer Space Antenna (LISA). Perturbation theory is commonly used to estimate the parameters that enter the calculation of gravitational wave spectra. However, perturbation theory is known to run into the infrared problem in the regime we are interested in and furthermore it is important to test the reliability of existing results. Here I will discuss our recent results where we studied a real singlet scalar model with a tree level potential barrier and performed nonperturbative simulations to determine the bubble nucleation rate. Our preliminary results show that higher orders in perturbation theory are necessary, and we expect our findings to allow calibration of the systematic uncertainty in perturbative results.

        Speaker: Anna Kormu (University of Helsinki)
      • 2:45 PM
        Lattice approaches to microphysical bubble dynamics 30m

        In the study of cosmological phase transitions, even apparently weakly coupled theories develop strongly coupled sectors. For static equilibrium quantities, lattice methods have been developed to tackle this which are able to yield unambiguously correct results up to small statistical errors. For real-time quantities, the problem is more complicated. In this talk, I will review approaches to using lattice simulations for studying real-time bubble dynamics.

        Speaker: Oliver Gould (University of Nottingham)
    • 3:15 PM 4:00 PM
      Coffee Break
    • 4:00 PM 5:00 PM
      Plenary session: Plenary II
      • 4:00 PM
        Electroweak sphaleron in a magnetic field 30m
        Speaker: Jaakko Annala (University of Helsinki)
    • 9:00 AM 10:00 AM
      Plenary session: Plenary III
      • 9:00 AM
        Complex Lagevin and QCD Thermodynamics 1h
        Speaker: Benjamin Jaeger (University of Southern Denmark)
    • 10:00 AM 10:45 AM
      Coffee Break
    • 10:45 AM 12:15 PM
      Plenary session: Plenary IV
      • 10:45 AM
        Lefschetz Thimbles and real-time dynamics 30m
        Speaker: Anders Tranberg (UiS - TN - IMF)
      • 11:15 AM
        Mitigating the sign problem with line integrals 30m
        Speaker: Rasmus Larsen
      • 11:45 AM
        Machine Learning assisted real-time Complex Langevin 30m
        Speaker: Alexander Rothkopf (UiS TN IMF)
    • 12:15 PM 1:45 PM
    • 1:45 PM 3:15 PM
      Plenary session: Plenary V
      • 1:45 PM
        Recent finite-volume developments in QED$_\textrm{L}$ 30m

        In this talk I will briefly present our recent RBC/UKQCD result for isospin-breaking corrections to leptonic decay rates. With the leading systematic uncertainty coming from unknown finite-volume effects, I will discuss the analytical evaluation of these at order $1/L^3$. This order is particularly complicated in certain formulations of finite-volume QED, and requires better understanding for future precision calculations in lattice QCD+QED.

        Speaker: Nils Hermansson-Truedsson (Lund University/The University of Edinburgh)
      • 2:15 PM
        Spectrum of QCD with one flavour 30m
        Speaker: J Tobias Tsang (CP3-Origins, The University of Southern Denmark)
      • 2:45 PM
        Complex heavy quark potential 30m
        Speaker: Gaurang Parkar (University of stavanger)
    • 3:15 PM 4:00 PM
      Coffee Break
    • 9:00 AM 10:00 AM
      Plenary session: Plenary VI
    • 10:00 AM 10:30 AM
      Coffee Break
    • 10:30 AM 11:25 AM
      Plenary session: Discussion - Lattice Activities in the Nordics
    • 11:25 AM 11:30 AM
      Conveners: Alexander Rothkopf (UiS TN IMF), Anders Tranberg (UiS - TN - IMF)