The IIIrd Nordic Lattice Meeting 2023

6 Jun 2023, 12:00 → 8 Jun 2023, 18:00 Europe/Oslo

UiS

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 (http://www.ydalir.no) and various hotels are available in the city center, 10 minutes from campus by bus.

Looking forward to seeing you in June,
Alexander & Anders

Tuesday, 6 June

12:00 → 13:00 Lunch

13:00 → 13:15 Opening

Conveners: Anders Tranberg (UiS - TN - IMF), Alexander Rothkopf (UiS TN IMF)

13:15 → 15:15 Plenary session: Plenary I

13:15 Phase transitions, gravitational waves and the 2-Higgs doublet model

Speaker: Kari Rummukainen (University of Helsinki)

norlat23.pdf

13:45 Bubble nucleation and quantum initial conditions in classical statistical simulations

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)

NordicLattice_Gerhard.pdf

14:15 Real scalar phase transitions: bubble nucleation, nonperturbatively

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)

Lattice-Kormu.pdf

14:45 Lattice approaches to microphysical bubble dynamics

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)

OG_Lattice.pdf

15:15 → 16:00 Coffee Break

16:00 → 17:00 Plenary session: Plenary II

16:00 Electroweak sphaleron in a magnetic field

Speaker: Jaakko Annala (University of Helsinki)

nordic_lat23_annala.pdf

Wednesday, 7 June

09:00 → 10:00 Plenary session: Plenary III

09:00 Complex Lagevin and QCD Thermodynamics

Speaker: Benjamin Jaeger (University of Southern Denmark)

NoLa2023.pdf

10:00 → 10:45 Coffee Break

10:45 → 12:15 Plenary session: Plenary IV

10:45 Lefschetz Thimbles and real-time dynamics

Speaker: Anders Tranberg (UiS - TN - IMF)

11:15 Mitigating the sign problem with line integrals

Speaker: Rasmus Larsen

Rasmus_Larsen_Nordic_2023.pdf

11:45 Machine Learning assisted real-time Complex Langevin

Speaker: Alexander Rothkopf (UiS TN IMF)

Complex_Langevin_Kernels_EXPORT.pdf

12:15 → 13:45 Lunch

13:45 → 15:15 Plenary session: Plenary V

13:45 Recent finite-volume developments in QED$_\textrm{L}$

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)

NHTNordicLattice2023.pdf

14:15 Spectrum of QCD with one flavour

Speaker: J Tobias Tsang (CP3-Origins, The University of Southern Denmark)

OneFlavour.pdf

14:45 Complex heavy quark potential

Speaker: Gaurang Parkar (University of stavanger)

nordic_lattice2023.pdf

15:15 → 16:00 Coffee Break

Thursday, 8 June

09:00 → 10:00 Plenary session: Plenary VI

09:00 Entanglement Entropy and Lattice Gauge Theory

Speaker: Tobias Rindlisbacher (University of Bern)

entanglement_and_lgt_optimized.pdf

10:00 → 10:30 Coffee Break

10:30 → 11:25 Plenary session: Discussion - Lattice Activities in the Nordics

11:25 → 11:30 Closing

Conveners: Alexander Rothkopf (UiS TN IMF), Anders Tranberg (UiS - TN - IMF)