• Tuesday 13 April 2021 at 10:15 with Zoom: Manuel Reichert (Sussex)
    Gravitational waves from first-order phase transitions with non-perturbative effective potentials
    Abstract: In this talk, I will present the gravitational-wave signals from the electroweak phase transition as well as from a dark SU(N) confinement-deconfinement phase transition. The common denominator is that the effective finite-temperature potential stems from a non-perturbative computation, in one case from the functional renormalisation group and the other case from the lattice.
    In the electroweak sector, I will detail the impact of non-perturbative higher-dimensional operators in the Higgs potential. Interestingly, the type of higher-dimensional operator seems to have no impact on the gravitational-wave signal, which leads to a universal relation between the mean-bubble separation and the strength parameter of the electroweak phase transition.
    In the dark sector, I will show how the confinement phase transition from a strongly coupled dark SU(N) sector can be computed via effective Polyakov loop models adapted to lattice data. This allows for an eagle view of the dark landscape which is spanned by the phase-transition temperature and the number of dark colours.
    The talk is based on
    – Universal gravitational-wave signatures from heavy new physics in the electroweak sector (
    – Testing the Dark Confined Landscape: From Lattice to Gravitational Waves (

  • Tuesday 20 April 2021 at 10:15 with Zoom: Mikko Laine (Bern)
    How well do we know the thermal photon rate?
    Abstract: The ALICE experiment at LHC has proposed to replace itself during Long  Shutdown 4 through a new experiment, aimed e.g. at studying the production  of very soft electromagnetic radiation (pT < 100 MeV). I review what 40+  years of theoretical research have taught us about the production of photons from a thermal QCD plasma. In particular, the prospects for constraining the  thermal photon rate through lattice QCD are discussed, pointing out that  there may still be room for new theoretical ideas in this field.

  • Tuesday 18 May 2021 at 10:15 with Zoom: Hans-Werner Hammer (Darmstadt)
    Unnuclear Physics
    Abstract: TBA

Hopefully the up to 50 min + 10 min discussion long seminar/colloquium will be understandable to a wide audience.
Contacts: Keijo Kajantie (keijo kajantie at helsinki fi) [ HIP seminar],
Sami Raatikainen (sami raatikainen at helsinki fi) [cosmo seminar]

New Nordic series of seminars over the web, link: 
For more information, and to subscribe to email announcements, contact Oscar Henriksson (oscar henriksson at helsinki fi)

Other related seminars

Friday 10-12 seminar series in A315:Astrophysics seminar.
Mathematical Physics Seminar and Workshop series Wed 14-16 in Exactum C123.