DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS 2026

• • Tuesday 27 October 2026 at 10:15 in A315 and using Zoom: Débora Mroczek (Turku)
    New phases of matter in neutron stars: are we there yet?
    Abstract: Advances in X-ray, radio, and gravitational-wave astronomy have enabled increasingly precise observations of isolated and merging neutron stars. Neutron stars have now been found with masses close to twice that of our Sun, suggesting that at the highest densities matter becomes much harder to compress, pushing back against gravity more strongly than ordinary nuclear matter would. Measurements of neutron-star radii and tidal deformabilities point in the same direction. This trend could signal the emergence of a new phase of matter in the cores of massive neutron stars. Yet drawing statistically robust conclusions about their composition remains difficult due to large theoretical and observational uncertainties. Central to this puzzle is the neutron star equation of state (EoS), the relation between pressure and density, which would carry the imprint of any such phase. In this talk, I will outline how statistical inference pipelines for the EoS are constructed, identify key sources of theoretical uncertainty, and discuss their current limitations. Finally, I will argue that valuable clues to the behavior of matter in neutron star cores may come not only from the skies, but also from first-principles calculations in the regime where quarks and gluons are weakly coupled.
  • Thursday 29 October 2026 at 10:15 in A315 and using Zoom: Guilherme Catumba (Milano)
    The non-perturbative matching of Magnetostatic QCD
    Abstract: High-temperature QCD can be described, through dimensional reduction, by a series of 3D effective field theories. Electrostatic QCD consists of a gauged-scalar theory, while magnetostatic QCD (MQCD) is a pure 3D gauge theory. The use of dimensionally reduced effective theories to predict 4D observables relies on the matching between the 3D and 4D theories, which, at present, is only known perturbatively.  We have devised a strategy to perform a fully non-perturbative matching of QCD  and MQCD via lattice simulations.  This allows us to assess the accuracy and validity  of the effective theory without perturbative uncertainties coming from the matching.  In this talk I will explain how the matching is performed over a wide range of temperatures with high precision, while keeping all lattice systematics under control. As a first step in this study, we investigate the matching between the finite temperature pure gauge theory and its 3D counterpart, for which I report some results.
    
  • Tuesday 3 November 2026 at 10:15 in A315 and using Zoom: Antti Hippeläinen (Helsinki)
    Probing hadronic structure with holographic methods
    Abstract: Gravitational form factors encode how mass, spin and internal forces are distributed inside hadrons, and they remain challenging to access. We discuss how holographic models of QCD offer a complementary route and present results obtained in improved holographic QCD and V-QCD for the proton, the pion, rho and a_1 mesons and glueballs. For mesons, the form factors are parameter-free predictions of the model. We close by discussing where the holographic description can be expected to be reliable, and what spin-1 states show about the limits of the mechanical interpretation.
  • Tuesday 17 November 2026 at 10:15 in A315 and using Zoom: Pablo Navarrete (Helsinki)
    The g^6 pressure of hot Yang-Mills theory
    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],
Tushar Gupta  (tushar.gupta at helsinki fi) [cosmo seminar]

Other related seminars

Friday 10-12 seminar series in D114: Astrophysics seminar
Mathematical Physics Seminar and Workshop series Wed 14-16 in Exactum C123.
InstituteQ Events and Seminars